We recently received the latest edition of the excellent book The Recumbent Bicycle, 3rd edition, by Gunnar Fehlau and published by Out Your Backdoor Press. It makes a great stocking stuffer at $22. The 3rd edition contains "greatly improved text and hugely improved photos—many of them new. It also includes an updated info resources appendix. It has much nicer coated paper and thicker cover stock."
The book contains a good history of recumbents, explaining why recumbents did not become more mainstream after being banned from professional racing in the early 1900's. Check out the table of contents.