Andreas Knipping 
German Express Steam Locomotives [PDF ebook] 

In this book, the author defines the express stem locomotive on the basis of the mandatory criterion of large drive wheels, and studies its evolution from around 1850 to the last refinements made around 1960, with many wrong turns and great successes along the way. This highly illustrated work features over 6, 000 German express steam locomotives, including the oldest, the 1A1 and the Crampton; the largest, the Prussian S3; the fastest, the Reichsbahn-05; arguably the most successful, the Bavarian S3/6; and the most powerful, the Bundesbahn’s oil-fired three-cylinder 01.