[1] E. N. Dancer: On the structure of solutions of non-linear eigenvalue problems. Indiana Univ. Math. Journ., 23, (1974), 1069-1076. DOI 10.1512/iumj.1974.23.23087 | MR 0348567 | Zbl 0276.47051

[2] M. Kučera: A new method for obtaining eigenvalues of variational inequalities of the special type. Preliminary communication. Comment. Math. Univ. Carol. 18 (1977), 205 to 210. MR 0435909

[3] M. Kučera: A new method for obtaining eigenvalues of variational inequalities. Branches of eigenvalues of the equation with the penalty in a special case. Časopis pro pěstování matematiky, 104 (1979), 295-310. MR 0543230

[4] M. Kučera: A new method for obtaining eigenvalues of variational inequalities based on bifurcation theory. Časopis pro pěstování matematiky, 104 (1979), 389-411. MR 0553173

[5] M. Kučera: A new method for obtaining eigenvalues of variational inequalities: Operators with multiple eigenvalues. Czechoslovak Math. Journ. 32 (107), (1982), 197-207. MR 0654056

[6] M. Kučera J. Nečas J. Souček: The eigenvalue problem for variational inequalities and a new version of the Ljusternik-Schnirelmann theory. In "Nonlinear Analysis", Academic Press, New York-San Francisco-London 1978. MR 0513782

[7] E. Miersemann: Über höhere Verzweigungspunkte nichtlinearer Variationsungleichungen. Math. Nachr. 85 (1978), 195-213. DOI 10.1002/mana.19780850116 | MR 0517651 | Zbl 0324.49036

[8] E. Miersemann: Höhere Eigenwerte von Variationsungleichungen. Beiträge zur Analysis, 17(1981), 65-68. MR 0663272 | Zbl 0475.49016

[9] E. Miersemann: Verzweigungnsprobleme für Variationsungleichungen. Math. Nachr. 65 (1975), 187-209. DOI 10.1002/mana.19750650118 | MR 0387843

[10] P. H. Rabinowitz: Some global results for nonlinear eigenvalue problems. Journ. Funct. Anal. 7(1971), 487-513. DOI 10.1016/0022-1236(71)90030-9 | MR 0301587 | Zbl 0212.16504

[11] E. Zeidler: Vorlesungen über nichtlineare Functionalanalysis I - Fixpunktsätze. Teubner Verlagsgesellschaft, Leipzig 1976. MR 0473927