Book series
This section contains book series, multi-volumes and collected works.
Cambridge Library Collection - https://libgen.st/search.php?req=Cambridge+Library+Collection&lg_topic=libgen&open=0&view=simple&res=25&phrase=1&column=def
Publishing History - https://www.publishinghistory.com/
A Series of Series - https://seriesofseries.com/
You can find a lot of collected works on 1337x compiled by workerbee:
workerbee - https://1337x.to/user/workerbee/
Book series by topic
Art
ART-COLLECTOR.RU Pictures Archive - https://rutracker.org/forum/viewtopic.php?t=939626
History of XX century in B/W photos:
https://rutracker.org/forum/viewtopic.php?t=1036836
http://static.rutracker.cc/old_attach/12401697.rar
Fiction
Delphi Complete - https://libgen.st/search.php?req=Delphi+Complete&lg_topic=libgen&open=0&view=simple&res=25&phrase=1&column=def
Harvard Classics - https://rutracker.org/forum/viewtopic.php?t=6244440
Library of America:
https://en.wikipedia.org/wiki/Library_of_America
Loeb Classical Library - https://libgen.st/search.php?&req=Loeb+Classical+Library&phrase=1&view=simple&column=def&sort=year&sortmode=DESC
Oxford World Classics - https://libgen.st/search.php?&req=Oxford+World%27s+Classics&phrase=1&view=simple&column=series&sort=year&sortmode=DESC
Penguin Classics - https://libgen.st/search.php?&req=Penguin+Classics&phrase=1&view=simple&column=series&sort=year&sortmode=DESC
Viking Portable Library - https://archive.org/search?query=title%3Aportable+AND+%28publisher%3Apenguin+OR+publisher%3Aviking%29
World’s Classics - https://seriesofseries.com/worlds-classics/
Bibliothèque de la Pléiade - https://www3.yggtorrent.wtf/torrent/ebook/livres/1045545-biblioth%C3%A8que+de+la+pl%C3%A9iade+-+116+volumes+pdf+djvu+fr
History
The Cambridge Ancient History
The New Cambridge Medieval History
The New Cambridge Modern History
https://rutracker.org/forum/viewtopic.php?t=5923844
Annals of America - https://rutracker.org/forum/viewtopic.php?t=6444536
Math
Graduate Studies in Mathematics - https://rutracker.org/forum/viewtopic.php?t=6299486
Graduate Texts in Mathematics - https://rutracker.org/forum/viewtopic.php?t=6003453
Undergraduate Texts in Mathematics - https://rutracker.org/forum/viewtopic.php?t=6003927
Springer Undergraduate Mathematics - https://www.springer.com/series/3423/books
Mir Publishers - https://archive.org/details/@mirtitles
Mathematischen Schülerbücherei - https://mathematikalpha.de/schuelerbuecherei
Philosophy
Great Books of the Western World - https://rutracker.org/forum/viewtopic.php?t=6244391
The Cambridge Edition of the Works of Immanuel Kant - Library Genesis
Klassiker Auslegen - https://libgen.st/search.php?req=Klassiker+Auslegen&open=0&res=25&view=simple&phrase=1&column=series
Society
Marx and Engels Collected Works - https://rutracker.org/forum/viewtopic.php?t=6244838
Marx’s Capital - https://rutracker.org/forum/viewtopic.php?t=6245165
Lenin Collected Works - https://rutracker.org/forum/viewtopic.php?t=6244821
Stalin Works - https://rutracker.org/forum/viewtopic.php?t=6244850
Trotsky Works - https://rutracker.org/forum/viewtopic.php?t=5351069