Sadly, these BMW books are out of print or have limited availability, but you can do an out of print search to try to find the book you need.

BMW 3-Series by Jeremy Walton.

BMW 503/507 : die V8-Sportmodelle by Georg Seeliger.

BMW 6-Series (High Performance Series) by Jeremy Walton.

BMW : A Celebration by Eric Dymock.

BMW : A History by Halwart Schrader.

BMW : Bavaria's Driving Machines by Jan P. Norbye.

BMW : Colour, Data and Detail on Four Decades of BMW Cars (Classics in Colour, No 7) by Martin Buckley, James Mann.

BMW Carbureted 2500, 2800, 3.0, Bavaria Shop Manual

BMW Classics (Osprey Classic Marques) by Jeremy Walton.

BMW Driver's Book (Foulis Drivers Book Series) by James Ruppert.

BMW M Series Performance Portfolio 1976-1993 (Brooklands Books) by R.M. Clarke.

BMW Since 1945 by Richard L. Busenkell.

BMW-Automobile : vom ersten Dixi bis zum BMW-Modell von morgen

Chilton's Repair and Tune-Up Guide BMW 1970-82 : 1600, 2000, 2002, 2002Tii, 2500, 2800, 2800Cs, Bavaria, 3000Cs, 3.0Cs, 3.0S, 3.0Si, 320I, 528E, 528I,
by Richard J. Rivele(Editor), et al.

Das weiss-blaue Wunder : BMW, Geschichte und Typen by Hanns-Peter Rosellen.