A lot of e-books don't have to be bought- they are downloaded.
sadly, tomb of the PzWaffe has no e-book english option so far.
Most of the really detailed books have no e-book option either.
yes , to be honest i have 249 pdf books and none were bought , no kidding , there is a lot of free ebooks sites , btw the list i mention are the ones im reading now , because like i said i have an extended library and my father was an history professor ( and later a Principal for 15 years , god rest his soul ) , so i have quite a library on me .