Published in Spring 1993 Zeiss Historica Journal
Author: Hans-Juergen Kuc
See Page 8 – 9.
Upon the publishing of his book (Auf den Spuren der Contax) in German, Mr. Kuc shared the table that he created to help identify the variants of the Contax I. The book would not be translated into English for many years but he did provide a full English explanation to Zeiss Historica.
To go to the Journal itself, click on the year 1993 in the first line above.