1. H. Brezis, L. Nirenberg, G. Stampacchia, A remark on Ky Fan’s minimax principle, Boll. Unione Mat. Ital. (4) 6 (1972), 293–300.
2. F.E. Browder, The fixed point theory of multi-valued mappings in topological vector spaces, Math. Ann. 177 (1968), 283–301.
3. F.E. Browder, On a sharpened form of the Schauder fixed-point theorem, Proc. Natl. Acad. Sci. USA, 74 (1977) 4749–4751.
4. J. Dugundji, A. Granas, KKM-maps and variational inequalities, Ann. Scu. Norm. di Pisa, V (1978), 69–682.
5. J. Dugundji, A. Granas, Fixed point theory, Vol. I, Monografie Matematyczne 61, Warszawa, 1982. Springer Monographs in Mathematics, Springer-Verlag, New York, 1982.