Denis Derdos, the author, used over 640 period technical manuals to provide accurate information:
Insight and period photographs are included. Note that French text has an olive background color while English text a blue-gray background color. After a while, your eyes will automatically seek the color, and therefore language, you prefer.
Personallu, I find the head on photos of stencils, plaques, and signage, to be immensely helpful to modeling the radios in scale. Scan and print onto decal paper or thin styrene (obviously, not on a laser printer for the latter):
The modern photographs of the actual items helps tremendously in getting details right...
Anecdotes are included and all photographs are sharp, clear, with accurate (French ) captions.
It is NOT a cheap book in any manner. However, it is a prized addition to my library and Heimdal Editions has already released book 2! The US distributor (who many times offers a discount. Hint: sign up for their newsletter to get a GREAT discount on a purchase) is Casemate USA.