Horex motorcycle books include the history of Horex motorcycles (German text) plus some manuals and brochures.
Horex was a motorcycle manufacturer in Bad Homburg, Germany. It was founded in 1923 by the Rex glassware company, which conflated Homburg and Rex to create the brand name.
Das Große Horex Buch by Jurgen Noll (2008)
Horex 2 Uberarbeitete Auflage by Karl Reese
Horex Motorräder (date unknown)
Cycle Magazine (1954) includes an article about the German Horex 350cc road racer.
Horex Prospekte 1921-60