Another resourse is through the book link on
http://www.earlytelevision.org. You are able to download (for free) the books to your computer/phone etc and read them. I purchased original hard copies of a lot of these book years ago and most go for $75 - $200 if you buy original copies. I read the downloaded copies of the books to keep my copies from wearing out. The book download link is:
http://www.earlytelevision.org/biblio.html