Here's an auction for an extermely rate (maybe one of a kind) 1988 Xerox PARC TIC MS-DOS Encyclopedia book.  The MS-DOS Encylcolpedia isn't so rare - what makes this book unique is that it came from the fabled Xerox PARC corporation which invented so much of the early PC computing innovations.  I found this book many lyears ago at a used computer sale in Palo Alto, CA.  It is an ex-libris book with the usual markings - but who knows who may have handled or referenced this book in the early days.  Maybe  Robert Metcalfe (Ethernet inventor) or  Douglas Engelbart (mother-of-all-demos) or ????  Who knows...  Yes, it's priced high - but you won't find another of these books with such an illustrious history floating around anywhere.....except maybe in a museum.