E. Szemerédi, G. Sárközy, J. Komlós, “Proof of the Seymour conjecture for large graphs”, Ann. Comb., 2:1 (1998), 43–60
2.
E. Szemerédi, A. Hajnal, “Proof of a conjecture of P. Erdös”, Combinatorial theory and its applications, Proc. Colloq. (Balatonfüred, 1969), v. II, North-Holland, Amsterdam, 1970, 601–623