The Open Syllabus collection contains WARC files from a mid-2021 crawl of about 50 million unique seed URLs extracted from the Open Syllabus version 2.6 dataset and their page requisites. The bulk of the seed URLs are from ".com", ".org", ".edu", and ".uk" TLDs.
These 1,200 very readable expository selections from over 400 authors and historical figures feature extensive comparison and trace the lineage of great thoughts.