Wealth of Esperanto books available
I'm just chiming in to announce to anyone who was unaware of this fact that there are several old-but-useful Esperanto books available for free through Google-Books.
All you have to do is go to GoogleBooks, do advanced book search, put "Esperanto" as your keyword. Choose your native language--ideally, English and select "Full View Only" then search. I get over 600 hits.
It seems like all the books are available for download in PDF format or you can view them in text-only format and copy and paste.