content: Beware of editions by General Books LLCThey produce books by scanning (OCR) copyright-free material, but without any editing.There are so many errors though that the result may be unusable.Usability probably depends on subject matter, but the many OCR-errors make even prose an annoying read.Especially mathematical and technical texts and texts with notes can become completely garbled.See the review of J.M. Keynes' "A treatise on probability" on this site which I bought but is useless, and similar comments by other buyers (on "Vanity Fair" by Thackeray; on "The Italian" by Radcliffe)