I think they got most of their material by hitting up their professors for old books. I got...
- The Tools of Social Science (1953)
- The Art of Scientific Writing: From Student Reports to Professional Publications in Chemistry and Related Fields (1987)
- On Writing Well (Third Edition, 1985)
- A Manual for Writers of Term Papers, Theses, and Dissertations (Fifth Edition, 1987)
- The Biologic Ages of Man: From Conception Through Old Age (1973)
- And for Mother Woot, a book about cancer and another book about home landscaping.
Literally all of these books are older than I am.