1. Coq formalization.
https://github.com/Abhishek-TIFR/List-Set
2. The Coq Standard Library.
https://coq.inria.fr/library/
3. Chudnovsky, M., Robertson, N., Seymour, P., Thomas, R.: The strong perfect graph theorem. Annal. Math. 164, 51–229 (2006)
4. Lecture Notes in Computer Science;C Doczkal,2018
5. Garey, M.R., Johnson, D.S.: Computers and Intractability: A Guide to the Theory of NP-Completeness. W. H. Freeman & Co., New York (1990)