Books on Trains

Books on prototypes:

Books on modelling

Ways to find/buy:

http://www.railpub.com/

http://books.google.com/books 

http://www.archive.org/details/texts 

http://www.bookfinder.com/ 

http://www.alibris.com/ 

http://www.abebooks.com/

http://www.railroadbooks.biz/