If you place an ad, someone could offer their 5 books ECO.
Where can I buy the entire ECO??????

I still have a copy of Chess Openings I.A. Horwitz when that teenage Mr Fischer in the early 1960's was starting to influence the game. I kind of know the feeling for having a written book
I would have thought "Learn" "Openings" on this site would prove to be useful.

I read a concise ECO book that shows all 500 ECO variations with one popular master game(full pgn/game) in each variation. Such kind of small ECO book is also interesting.

Other than library purpose, Printed ECO isn't useful. The latest Fritz Power Books is more up to date and useful. Some private Openings Book in Talk chess are even stronger.for engine competition.

Other than library purpose, Printed ECO isn't useful. The latest Fritz Power Books is more up to date and useful. Some private Openings Book in Talk chess are even stronger.for engine competition.
I agreed, computer analysed opening books could be much stronger than human book, but the best opening for you would be the one that you know about the plan from opening to ending.
These perfect book and brainfish database are assumed as one of the best opening books
https://sites.google.com/site/computerschess/perfect2018books
About eight years ago:
https://web.archive.org/web/20140627063241/http://www.chesscafe.com/text/hansen145.pdf
The informant store only has two of the five volumes.
https://www.sahovski.com/ECO-Encyclopedia-of-Chess-Openings-c25038053