Published in Spring 1989 Zeiss Historica Journal
Author: Charles Barringer
See Page 3 – 9.
The author contributes a considerable amount of research into the telephoto Sonnar lenses and the accessories including reflex housings, viewfinders, riflescopes and other important devices to promote the use of these breakthrough lenses.
To go to the Journal itself, click on the year 1989 in the first line above.