Here are some books that deal with the history of Unix and its early days.

Life_with_Unix.pdf
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In January 2016, Don Libes and Sandy Ressler donated a copy of their
wonderful book to the archive. Sandy's e-mail says:

   Don forwarded your email about getting an electronic copy
   of Life with Unix...it's attached as a PDF!
   It should be cool to make it available (and Don and I agree that is
   fine)...we also at some point a few years ago got Prentice-Hall to give
   us the copyright or to at least say do whatever you want with it. Of
   course I can't find that email but it should be fine. There are of
   course illustrations in the book that are copyright by others that we
   obtained permission to use in the book so we can't give permission for   
   those...however I doubt that would be a real issue with anyone....so
   feel free to use this in your archive...take care...Sandy
   PS this is probably a pdf of the very first version/printing of the
   book with no subsequent corrections