1
Eells J. A setting for global analysis[J]. Bulletin of the American Mathematical Society, 1966, 72(5): 751-807.
2
E H Rothe. Critical Point Theory in Hilbert Space under Regular Boundary Conditions. 1971.
3
Minty G J. Two theorems on nonlinear functional equations in Hilbert space[J]. Bulletin of the American Mathematical Society, 1963, 69(5): 691-692.
4
Darinskii B M, Sapronov Y, Tsarev S L, et al. Bifurcations of extremals of Fredholm functionals[J]. Journal of Mathematical Sciences, 2007, 145(6): 5311-5453.
5
Kirchgassner K. Multiple Eigenvalue Bifurcation for Holomorphic Mappings[C]., 1971: 69-99.
6
Zeidan V, Zezza P. Necessary conditions for optimal control problems: conjugate points[J]. Siam Journal on Control and Optimization, 1988, 26(3): 592-608.
7
Rothe E H. Remarks on the application of gradient mappings to the calculus of variations and the connected boundary value problems in partial differential equations[J]. Communications on Pure and Applied Mathematics, 1956, 9(3): 551-568.
8
Bobylev N A, Yanov S V, Korovin S K, et al. Topological Characteristics of Extremals of Variational Problems[J]. Journal of Mathematical Sciences, 1999, 78(4): 155-268.