Kneser's conjecture, chromatic number, and homotopy

Borsuk, 1933, Drei Sätze über die n-dimensionale euklidische sphäre, Fund. Math., 20, 177, 10.4064/fm-20-1-177-190 Erdös, 1966, On chromatic number of graphs and set-systems, Acta Math. Acad. Sci. Hungar., 17, 61, 10.1007/BF02020444 Erdös, 1967, Kromatikus gráfokról, Mat. Lapok, 18, 1 Garey, 1976, The complexity of near-optimal graph coloring, J. Assoc. Comput. Mach., 23, 43, 10.1145/321921.321926 Stahl, 1976, n-tuple colorings and associated graphs, J. Combinatorial Theory Ser. B, 20, 185, 10.1016/0095-8956(76)90010-1 Kneser, 1955, Aufgabe 300, Jber. Deutsch. Math.-Verein., 58