http://nuclearcdboxafziza4mgohcwhzfjiyg6zeslnry33pepsgtur2wyeyd.onion/social/thread/69.html
Of course, with the complexities of international copyright law, and the difficulty of censoring distributed information, many of these are 'shadow libraries', operating without respect for bourgeois copyright law. Famous examples are Z-Library (z-lib), Library Genesis (LibGen) and Sci-Hub.