1. Existence of closed geodesics on positively curved manifolds;Ballmann, W.;J. Differential Geometry,1983
2. I. Beach, A. Nabutovsky, and R. Rotman, Quantitative Morse theory on free loop spaces on Riemannian 2-spheres, In preparation.
3. Genericity of nondegenerate geodesics with general boundary conditions;Bettiol, Renato G.;Topol. Methods Nonlinear Anal.,2010
4. G. D. Birkhoff and M. R. Hestenes, Generalized minimax principle in the calculus of variations, Proceedings of the National Academy of Sciences of the United States of America 21 (1935), no. 2, 96.
5. The structure of the cut locus in dimension less than or equal to six;Buchner, Michael A.;Compositio Math.,1978