Udo Krämer: Second-hand! The alternative - first-hand tips for second-hand devices
The indispensable helper for buying used 35mm cameras, lenses, flash units and accessories. Selection, condition, functional testing, minor repairs, restoration and power supply are described in detail.
Gebraucht die Alternative
This book from 1997 is also only available in German, but can be translated using Google Translate on a smartphone, for example.
It introduces various 35mm cameras, lenses as well as accessoires and gives useful practical tips for checking and caring for used cameras.
The book was written during the heyday of analog cameras and is therefore very close to the topic.