Published in Autumn 1993 Zeiss Historica Journal
Author: Simon Worsley
See Page 11 – 14
The author has made an extensive examination of the serial numbers of Zeiss Ikon cameras and Carl Zeiss Jena lenses from the era in the title and explains the eccentricities in the process and an explanation on how best to date the lenses and cameras.
To go to the journal itself, click on the year 1993 in the first line above