Discrete Mathematics using a Comptuter (O’Donnell, Hall, Page) Chapter 2
https://runestone.academy/ns/books/published/dmoi-4/sec_logic-proofs.html
https://runestone.academy/ns/books/published/dmoi-4/sec_logic-structures.html
https://runestone.academy/ns/books/published/dmoi-4/sec_logic-conc.html
https://runestone.academy/ns/books/published/DiscreteMathText/chapter4.html
https://runestone.academy/ns/books/published/DiscreteMathText/directproof4-1.html
https://runestone.academy/ns/books/published/DiscreteMathText/rationals4-2.html
https://runestone.academy/ns/books/published/DiscreteMathText/divisibility4-3.html
https://runestone.academy/ns/books/published/DiscreteMathText/cases4-4.html
https://runestone.academy/ns/books/published/DiscreteMathText/contradiction4-5.html
https://runestone.academy/ns/books/published/DiscreteMathText/morecontradiction4-6.html
https://www.cs.carleton.edu/faculty/dln/book/ch04_proofs_2021_September_08.pdf
The Haskell Road to Logic, Math and Programming (Doets, van Eijck) Chapter 3
https://www.youtube.com/playlist?list=PLZh9gzIvXQUtB1t57_Xyk3yp9MK2iIFXX