The Pentacon Six System
by TRA

Publicity for the Praktisix and Pentacon Six System
Produced by Distributors

In some countries, distributors and even some retailers produced publicity materials on the Praktisix/Pentacon Six system: cameras, lenses and accessories.  Here we are looking at publicity that goes beyond advertisements placed in other publications.

On this page we focus on distributors outside East Germany, but start with early literature from an exporter in East Germany.

East Germany, 1957


Substantial booklet in four languages: German, Russian, English and French
Approximate dimensions: 150mm × 209 mm
48 pages

This brochure was published by the Deutsche Export- und Importgesellschaft Feinmechanik-Optik MBH, which was located in the Russian-occupied sector of Berlin.  As can be seen from the front cover, it is here giving especial emphasis to the new Praktisix medium format camera from KW in Dresden.

Other items featured are Praktica and Praktina cameras, including two motor drives and a 17 metre film back for the Praktina.  Other cameras include the Pentacon F (formerly known as the “Contax”, until this name was disputed by the West Germans), the Pentacon FB with non-TTL metering pentaprism, the Exakta Varex and Exa and a wide range of other cameras from various manufacturers in the Eastern Zone of Germany, including the Weltaflex 6×6 twin-lens reflex, the Altix and the Werra.  There are also lenses from Zeiss (but not for medium format, an 8mm movie camera, a 16mm movie camera, a massive wooden studio camera for 13×18 and 18×24 cm formats, enlargers, projectors (still and movie), a hand-held light meter, episcope, Arnz filters, binoculars, machinery for sound movie studios, etc.

Click on the image here to see the front of the booklet full size.


Page 3 of this booklet gives a brief description of the Praktisix.  The lens in the photograph is an 80mm f/2.8 Carl Zeiss Jena Tessar, although only the word “Jena” can be clearly seen, no doubt to permit the use of this photograph in any market world-wide (although the name “Carl Zeiss Jena” and the lens name “Sonnar” are used elsewhere in this booklet.

Below, we show three further pages from this booket.

Click on the image here to see page 3 of the booklet full size.


The first of the pages that present lenses from MEYER-OPTIK Feinoptisches Werk - Görlitz features the 80mm f/3.5 Primotar E, which had been designed for the Praktisix.  It is described as being equipped with an “innovative spring aperture mechanism”.  This was the precursor to the fully automatic aperture that was offered on the Tessar and subsequently on all other Carl Zeiss Jena lenses for the Praktisix and the Pentacon Six (other than the mirror lens).

The text on the Meyer lens is spread between pages 31 and 32, depending on the language, the English text being on page 32, which is reproduced to the right.

Click on the image here to see page 31 full size.


The next two pages feature two further Meyer-Optik lenses: a 35mm wide-angle lens and the 300mm f/4.5 Telemegor telephoto lens.  Both of these lenses are described as being “coated”, and for 35mm cameras – at least, that is what the German text states; the English and French is a lot more vague.  As we are aware from other publicity, the 300mm Telemegor was also soon being offered for the Praktisix, and remained available for this camera for many years.

Click on the image here to see pages 32 and 33 full size.

West Germany, 1959


German-language leaflet
Approximate dimensions: 150mm × 210 mm
8 pages

This leaflet has the title “PRAKTICA – PRAKTINA – PRAKTISIX PREISLISTE Oktober 1959”.  Page 1 (not reproduced here) starts with the KW logo, and the leaflet ends with the same logo on p. 8 (see to the right here).

Information on the Praktina II A is listed at the top of this page, followed by details of the first version of the Praktisix.  We note that all three of the early 80mm lenses for the Praktisix are listed, the Meyer Primotar, the Jena Tessar (here called “Jena T”) and the Biometar (here called “Jena Bm”).

We also note that the plain prism is listed, as are the manual tubes and various focussing screens.  The angle finder for the prism is described as “in Vorbereitung” (
“in preparation” or “forthcoming”).

Click on the image here to see this page full size.  With some browsers, clicking a second time will enlarge the page further.  


Page 8 gives us further information on the source of this leaflet.  The full name of the Dresden manufacturer, KW, is given.  Since autumn 1945 it had found itself in the Soviet Occupation Zone of Germany (East Germany).  KW’s name is followed by the details of the General Respresentative and supplier for Bavaria (West Germany).  Prices are in West German DM (Deutschmarks).

The leaflet may have been printed in East or West Germany.  The poor quality paper leads us to suspect East Germany, where poor quality paper was frequently used right up to the end in 1989.  However, this was published only 14 years after the end of the war, and the West German “Economic Miracle” had not yet happened, so we cannot exclude the possibility that this might have been printed in West Germany, in collaboration with KW.

Few lenses are listed, but all three of the 80mm lenses are of course there, as well as the 65mm Flektogon, the 120mm Biometar, and the older 300mm Meyer Tele-Megor.  Two West German lenses, both from Kilfitt, are also listed: the 90mm Makro-Kilar (see here) and the 300mm Pan-Tele-Kilar (see here).  Like this distributor for KW, Kilfitt was located in Munich.  At 438DM, the Makro-Kilar was apparently 6DM more expensive than in 1966 (see below), but here it seems to include the Praktisix mount, for which the user had to pay a further 48DM in 1966.  The Pan-Tele-Kilar (plus mount!) is the same price as in 1966. 

Click on the image here to see this page full size.  With some browsers, clicking a second time will enlarge the page further.
France, 1960


French-language booklet
Approximate dimensions: 158mm × 240 mm
16 pages

This booklet is from the French company
Établissements H Marguet of rue Crozatier, Paris XIIe, which describes itself as “Concessionnaires Exclusifs”, which means “Exclusive dealers”.  The booklet principally features KW’s Praktica IV A and Praktina IIA cameras, but on the final page of text also features the Praktisix, for which see details to the right.

Click on the image here to see the front of the booklet full size.


Page 15 compares the Praktisix with the Praktina and states that it “is endowed by the technicians of KW with many of the perfections tested for several years in the small format.”

It points out that the wide screw bayonet mount is robust and reliable and eliminates all vignetting, while the lenses have automatic aperture without any need to be cocked in advance, and with internal transmission.  It then states that the Praktisix has two viewfinders, and the prism is the first in the world for a 6×6 camera.

The shutter has a continuous range of speeds from 1 second to 1/1000 sec plus B, and speeds can be selected before or after advancing the film.

Many of these details refer to the limitations of many other cameras that were on the world market at the time.

We note the choice of three different 80mm lenses, plus the 65mm wideangle, the 120mm Biometar and the 300mm f/4.5 Meyer Telemegor.

The bottom of the page states, “Delivery in 1961”, which suggests that stocks of the camera, lenses and accessories had not yet reached France.

Click on the image here to see page 15 full size.

West Germany, 1965


German-language leaflet
Approximate dimension: 150mm × 210 mm
6 pages

This leaflet was produced by a West German photographic distributor in Munich called » REFLEX «, the same company named on the 1959 leaflet shown above.  This leaflet lists East German cameras from KW (the manufacturers of the Praktisix) and Pentacon, as can be seen from the final page of the leaflet:


As well as listing lenses for 35mm cameras from the East German firms of Meyer (Görlitz), Ludwig (Dresden) and what they call “Jena” (i.e., Carl Zeiss, Jena), they also list lenses from the West German firms of Hertel & Reuss (monoculars only, with adapters for various cameras), Enna (Munich), Isco (Göttingen), Kilfitt (Munich), Schacht (Ulm), Schneider (Bad Kreuznach) and Steinheil (Munich).  The Praktisix II is prominently featured on page 1 and on page 5.

Click on the images here to see them full size.


The number of accessories listed for the Praktisix II is impressive, showing availability of most items that were also offered offered for the subsequent Pentacon Six (TL) throughout the decades of its production run.

The metering prism, launched in 1968, is of course not here, but the plain prism is, as would be expected, as it was listed in some of the publicity in earlier years (including the 1959 West German leaflet and the 1960 French booklet, above ).

Prices are listed in West German DM.  In 1965, the British Pound was worth DM11.20 and US$2.80 (according to this website, accessed on 4th March 2022).

As well as the Carl Zeiss Jena 50mm, 65mm, 80mm, 120mm and 180mm lenses, and the 1000mm mirror lens, there are lenses from Meyer Optik, Görlitz, the Kilfitt 90mm Macro-Kilar and 300mm Pan-Tele Kilar and the Enna 400mm Tele-Ennalyt.

Click on the image to see it full size.
West Germany, 1966


German-language leaflet
Approximate dimensions: 150mm × 210 mm
4 pages

This leaflet has the title “PRAKTICA – PRAKTISIX – OBJEKTIVE – ZUBEHÖR PREISLISTE JULI 1966” (“PRAKTICA – PRAKTISIX – LENSES – ACCESSORIES PRICE LIST JULY 1966”).  Some accessories for the Praktica IV, IV F and Nova are listed at the top of this page and at the bottom of page 4.

The name of the publisher is not stated, but the leaflet is written in German and the prices are in West German DM (Deutschmarks), so it must be from (or for use by) a distributor or retailers in West Germany prior to the establishment of the Beroflex
company (see below).  It is the same size as the West German 1959 price list shown above, but KW is no longer named (no doubt a reflection of its incorporation, at the insistence of the East German State or the Soviet authorities, into the Pentacon organisation).

Click on the image here to see this page full size.  With some browsers, clicking a second time will enlarge the page further.  

(Incidentally the page number is given as “ – 5 – ”.  However, this must be a printing error; this is a four-page leaflet, and the next page is labelled “ – 4 – ”.  This is page 3.)


Page 4 continues with the accessories for the Praktisix, and then comes a very interesting table with the lenses for the Praktisix.  Of the lenses listed a few years later for the “mature” Pentacon Six system, only the 300mm Carl Zeiss Jena Sonnar is missing.

Perhaps of more interest is the inclusion of the 90mm Kilfitt Makro Kilar.  The price is apparently only 6DM more than the 80mm Biometar, but one needs to add to this the price of the “WESI” mount for a further 48DM, which is listed but not named.  (Details of the lens here)

We also note the 300mm Kilfitt Pan-Tele-Kilar, which at 993DM (plus DM66 for the ANSIX mount!) is over 2½ times the price of the Meyer Tele-Megor.  (Details here)

The 400mm Enna Tele-Ennalyt is also listed (570DM).  (Details here)  All three of these West German lenses have manual aperture operation only.

A note at the foot of both pages states that these are recommended guide prices, so they may have been discounted by some vendors.

Click on the image here to see the last page of the leaflet full size.
USA, 1966


English-language brochure
Approximate dimensions: 217mm × 281mm (8½" × 11")
Four pages

Although it is undated, the date of this brochure can be established on the basis of the items listed, their prices and the statement on page 2 (not reproduced here), “This ad is appearing in Popular Photography, Modern Photography and other leading photographic magazines.”  The photograph used is the same one that was used in the two 1966 advertisments shown here, and the price is the same as in the October advertisement.

We note that in the USA they are not yet listing the Praktisix IIA.

Click on the image here to see the front of the booklet full size.  Please note that a standard A4 European scanner does slightly crop the left and right edges of the page.


Here we reproduce page 4 of this brochure, which lists the items available in the USA at that time, along with their prices in US dollars.

We note the absence of even the Meyer 300mm f/4.5 Telemegor, but the presence (with “limited availability”!) of an “automatic” 240mm Telephoto lens with the name Caspeco, which appears to be a lens that was not known in Europe.

Click on the image here to see page 4 full size.

France, 1967-69


French-language leaflet

This was received in electronic format, so it is not possible to be certain of the dimensions, but similar brochures in German are 210mm tall, and it is reasonable to assume that this will have been the same.

One sheet with multiple vertical folds.  It is probable that there is a further flap on the left, folded under in this photo, as it probably contains information on accessories for Praktica 35mm cameras (assuming that the content is similar to the German-language version).

Click on the image here to see it larger.

This leaflet is not dated, but the Pentacon Six faceplate was used on these cameras between approximately 1967 and 1969.  See here.  The lens style is that seen on some 80mm Biometar lenses manufactured in 1964 and Pentacon Six brochures produced in 1966 and 1967 show lenses with this finish.  See here.

The German-language version of this leaflet is also undated, although the same “man in bowler hat” photo was used on another German-language leaflet dated 1969.  The German phrase often (always?) used with this photo was “... wissen Sie was scharf ist?” (“... do you know what sharpness is?”).

We see that at this time the the camera was still being distributed in France exclusively by H. Marguet, based in Paris.

It is possible that this leaflet was produced in East Germany for use by the French distributor.  The German-language version seen seems to have been produced for a West German distributor in Hamburg.  In the German-language version, the other side of the sheet gives information on the PRAKTICAnova, PRAKTICAnova B and PRAKTICAmat 35mm cameras.

In German the man was referred to as the “Mann mit Melone” and Jehmlich states (p. 188) that the image was criticised by the East German communist authorities as “unsozialistisch” (“uncommunist”?).  Perhaps the tie and the hat suggested to them a western (English?) middle-class office worker.  For details of Jehmlich’s book, see the Bibliography page, here.

France, 1970 ...


French-language booklet
Approximate dimensions: 90mm × 205mm
32 pages plus one fold-out flap

We note that the distributors have changed.  Distribution is now in the hands of Compagnie Générale de Physique of boulevard de la Bastille, Paris 12e.  They describe themselves as “Agent Exclusif en France”. which means “Exclusive Agent in France”.

This brochure is undated, but the contents enable us to date it to within a year or two.  (Production dates are from Hummel, unless indicated otherwise.)
The Praktica Nova 1 B was produced from 1967 until 1975.  The Pentacon Super was launched in 1968 and ceased production in 1972.  The Praktica Super TL, also listed, appears to have been launched in 1968 (Jehmlich, p. 107) and continued in production until 1976 (Jehmlich, p. 232).  The Praktica LLC was introduced in 1969 and produced until  1975.
First production examples of the Pentacon Six TL seem to date from 1969, although on the earliest examples, the “TL” has been added under the name, instead of on the same line of text.  See here.
We also note that the UK distributor brochure, apparently from 1972, no longer lists the Praktica Nova 1 B, the Praktica Super TL or the Pentacon Super.

Click on the image here to see the front of the booklet full size.


Pages 14 and 15 contain details of the Pentacon Six.  The designation “TL” is not included in the page title, but is visible on the camera, and the descriptions on both pages refer to the TTL metering prism.

The description on page 14 refers to the possibility of obtaining 24 exposures by using 220 film.

We note that the 65mm Flektogon is still listed and that the Meyer 300mm f/4.5 Telemegor has been replaced with the Meyer 300mm f/4 Orestegor, and that the 500mm Orestegor is also listed.  The 300mm f/4 Zeiss Sonnar is also listed, here designated “S”.

The 80mm Biometar (here called “Bm”) is the only 80mm lens listed: the Meyer Primotar and the Zeiss Tessar are no longer offered (as indeed we would expect, from the lens publicity, here).

Click on the image here to see pages 14 and 15 full size.


The summary table on pages 18 and 19 lists all the lenses offered by the distributor, with a convenient separate column for the Pentacon Six.  We note here, as elsewhere in the brochure, that the name “Zeiss” is nowhere mentioned, and the lenses are described as “aus Jena”.

We note one error on the chart.  The 500mm Zeis (“aus Jena”) lens is listed as also available for the Pentacon Six.  We believe that this has never been the case.  This lens was also listed in a 1963 camera leaflet from France, but not in the East German camera leaflet of the same year.  (See here.)

Click on the image here to see pages 18 and 19 full size.


Finally we reproduce pages 20 and 21 (although the listing of accessories for the Pentacon Six continues all the way to page 25, alongside equivalent items for other cameras).  Readers interested in obtaining the original manufacturer codes for Pentacon Six accessories will find most of them listed on these pages.

Click on the image here to see pages 20 and 21 full size.
England, 1972 ...


English-language booklet
Approximate dimensions: 152mm × 222mm
40 pages on high-quality glossy paper, with full-colour printing on many pages.

This brochure (which they call a “Catalogue”) was produced by C.Z. (i.e., Carl Zeiss) Scientific Instruments Ltd and Carl Zeiss Jena Ltd, the companies that were the U.K. importers and distributors of the Pentacon Six, Praktica cameras and many other Carl Zeiss items from the end of the 1960s until the collapse of the East German régime and, with it, most East German industry in the months following the tearing down of the Berlin Wall in November 1989.

It is undated, but details of the contents (including some items from other countries) point to it having been produced in 1972 or very shortly thereafter.  Also, on page two of the brochure they state, “As a result of our rapid expansion, we found it necessary, at the beginning of 1971, to move our Service Department into new premises”, a clear indication that the brochure could not have been produced before late 1971, at the earliest.  At the time, “C.Z.”, as it was commonly referred to in the UK, was in New Cavendish Street, London.  A few years later, they moved a few miles further north, to Borehamwood in Hertfordshire.

Click on the image here to see the front of the booklet full size.


Click on the image here to see these pages full size.

In a magnificent two-page spread across the middle pages of this booklet, C.Z. presents the Pentacon Six TL.

Their description starts with the following two paragraphs:
“The Pentacon-six TL is a unique camera in that it provides the extra quality inherent in the 2¼" sq. format whilst maintaining the ease of use of a 35mm reflex camera.  It has become the first choice of professionals and advanced amateurs throughout the world who appreciate the outstanding quality of the Zeiss lenses, large format and facility for taking 24 exposures on 220 film at a single loading.

“The Pentacon-six TL is a complete system camera: nine different lenses, four finder systems, six focussing screens and accessories to cover virtually every conceivable application.”

The statements about the system in the second paragraph are not opinions; they are factually correct.


The next two pages of the booklet give comprehensive information on the lenses and accessories for the Pentacon Six.  It is interesting to see the official prices for these items.  (These prices were routinely undercut by retailers.)

We note that the 1000mm Zeiss mirror lens is the only one for which a price is not given.

Beneath the information on the 80mm Biometar standard lens, we note the photograph of leading British actor of the time, Richard Burton, as King Henry VIII in the 1970 film “Anne of the Thousand Days” (another indication that this brochure was probably produced not much later than about 1972).

Click on the image here to see this page full size.


Page 23 describes the accessories and lists most of them.  We note that, again, recommended retail prices for most items are given.

There are two illustrations that are incorrect:  the bellows that are shown are for a Praktica 35mm camera, not the Pentacon Six.  However, the Pentacon Six bellows were sold in the U.K., and five years after the probable publication date of this booklet, I bought mine, second hand, in a photography shop just beside Charing Cross Station in London, at a price of £26.00, which struck me as quite reasonable for such a specialist item.  I still use them, so have definitely got my money’s worth out of them.

The second incorrect illustration is the item described as “ ‘Z’ Ring and Double Cable Release”.  Again, the version for Pentacon’s 35mm cameras is shown.  However, I don’t doubt that the correct item would have been supplied if ordered.  (I bought mine in East Germany in 1978.)

C.Z. may have knowingly used the incorrect photographs, lacking suitable photographs of the Pentacon Six version of these items and assuming that few customers would notice the difference.  (I have only just spotted it, about forty years after first getting a copy of this booklet!)

Click on the image here to see page 23 full size.

USA, 1972


English-language brochure
Approximate dimensions: 217mm × 281mm (8½" × 11")
Eight pages, plus a full-page insert on the Exa 1a, the Beirette, the Certo KN 35 and a light meter

Although it is undated, this brochure comes with a four-page insert titled “EXAKTA – PENTACON Price List January 1972”, and the items in the price list match the items in the brochure.


Here we reproduce the back cover of this brochure, which is dedicated to providing information on the Pentacon Six.

We reproduce below two further pages from the same brochure, which contain more information on the Pentacon Six.

Click on the image here to see the back cover of this brochure full size.


We here reproduce two facing pages from the brochure: pages 6 (here) and 7 (to the right).

The claim “World’s only 2¼ sq. SLR System with Exposure Insurance” presumably refers to the TTL metering pentaprism.

Hasselblad did introduce a metering prism in 1971, the 52051, but most professional photographers were extremely averse to through-the-lens metering for many years, preferring at most a hand-held meter that would measure incident light, as opposed to the reflected light readings used by all TTL meters, and so the Hasselblad prism was apparently only sold in small numbers.  In fact, many professionals boasted of their accuracy in assessing light intensity, and disdained using any light meter at all.  They mostly got away with this by shooting in black-and-white, where most film emulsions had a fairly wide lattitude and so incorrectly-exposed shots could to some extent be rescued by careful printing on paper with the right contrast grade.

Pentacon was three years ahead of Hasselblad in bringing a metering pentaprism for a medium format camera to the market, and its prism was more compact, and much easier to use.  (I had a 52051 on a Hasselblad 500C, and eventually sold both the camera and the metering prism.)

Click on the image here to see page 6 full size.


We note from this page that the 65mm Flektogon is no longer listed – although it is shown in the photograph at the bottom of page 6.  (It is the wide-angle lens on the left, next to the 500mm Pentacon.)

We also note that this brochure was produced at a time when Pentacon was promoting the use of the name “Pentaconar” for the Meyer-Optik lenses.  (See the 1970 lens brochure from Pentacon, here.)

Page 7 (reproduced to the left here) starts with more information on the metering pentaprism.

One printing error is observed on this page: “Autmatic shutter cocking device after 12th and 24th frames” must mean “Automatic shutter locking device after 12th and 24th frames”.

Click on the image here to see page 7 full size.


West Germany, 1972


German-language brochure
Approximate dimensions: 148mm × 210mm
Twenty-eight pages

This is not a brochure for the consumer but a price list for the West German camera trade.  It serves, for us, as an introduction to the West German importer and distributor of photographic goods from East Germany and from some other eastern European (communist) countries.  Beroflex was founded by Heinrich Mandermann and Herbert Kohler in 1969 (Barry M. Jones, p. 119).

Click on the image here to see the front of this brochure full size.

(See Jones, Barry M, “From KW to Pentacon: The story of Kamera Werkstätten, Praktica and Pentacon cameras”, published by the author in 2014.)


We here reproduce pages 16 and 17 of the same brochure.

Note that as this is for the trade, prices are nett and do not include Value-Added Tax (“Mehrwertsteuer”, abbreviated “MWSt.”).

We note that on page 17 the 65mm Flektogon is not listed – nor is the 300mm Sonnar.  Obviously, for use in West Germany, the disputed name “Zeiss” is not used, nor are the lens names “Biometar” and “Sonnar”.

We note the extremely high price, in West German Deutschmarks (“DM”) of the 1000mm mirror lens.

Click on the image here to see these pages full size.

West Germany, 1976-78


German-language brochure
Approximate dimensions: 152mm × 210mm
Thirty-two pages (including the cover)

The page-numbering of this brochure is non-standard, with the first page of text, which is a right-hand page, being numbered “2”.

This brochure was apparently published in March 1976 (code on the last page), but it was sent to me by Beroflex’s West Berlin office in 1978 while I was living in West Germany, so it was still their current brochure then.

Click on the image here to see the front of this brochure full size.


Here we reproduce page 21 of the brochure.  Pages 22 and 23 are reproduced below.

We are surprised to note that the 65mm Flektogon wide-angle lens is listed here, even although it had not been available in East Germany for a number of years.  Perhaps Beroflex had some old stock that they wished to sell off ...

All the expected lenses are here, including the 300mm Zeiss Sonnar (here called “JENA S aus Jena”), both Meyer-Optik lenses (here called “PENTACON (Orestegor)”, not “PENTACONAR”) and the 1000mm mirror lens.

Click on image here to see page 21 full size.


Pages 22 and 23 contain a full listing of accessories for the Pentacon Six TL, along with a detailed description of each item.

Prices for East German cameras and photographic accessories were extremely high in East Germany, where they were sold in various government-owned stores.  But for visiting West Germans, the prices were very reasonable, even at the official exchange rate, which was 1 East German Mark for one West German Deutschmark.  However, West Germans with trusted contacts in East Germany often received four East German Marks for every one West German Deutschmark, as East Germans were desperate to get western currencies and could spend this precious “hated”, “capitalist” currency in the special Government-run Intershops, where they could buy goods unobtainable anywhere else in East Germany, from foreign chewing gum and cigarettes to Black & Decker power tools, cement for household repairs, or colour televisions that would pick up the supposedly-forbidden West German television in colour.  (West Germany used the colour standard used throughout most of western Europe except France, PAL, while East Germany used a Russian-modified version of the French SECAM system.)

Click on image here to see page 22 full size.


Here we reproduce page 23 of the same brochure.

Here are a few examples of prices in Government shops in East Germany in 1978, what these items would have cost many visiting West Germans, in DM, and, for comparison purposes, approximate UK Pound Sterling equivalents at the time.

Approx £ sterling
Angle finder
Focussing telescope
Automatic Extension tubes (set of 4)
Special aperture-control ring

Pound sterling:DM exchange rate for May 1978 taken from on 19th August 2018, using the approximate average rate of £1 = DM3.84

Click on image here to see page 23 full size.

To go back to the beginning of the literature section, click here.


© TRA August 2018  Revised: May 2023