1. R. Abraham and J. Robbin, Transversal Mappings and Flows, W. A. Benjamin, Inc., New York, 1967.
2. R. A. Adams, Sobolev Spaces, Academic Press, New York, 1975.
3. A. Ambrosetti, Some remarks on the buckling plate problem for a thin clamped shell, Ricerche Math. 23 (1974), 161–170.
4. A. Ambrosetti and G. Mancini, Sharp nonuniqueness results for some nonlinear problems, Nonlinear Anal. 3 (1979), 635–645.
5. A. Ambrosetti and G. Prodi, A Primer of Nonlinear Analysis, Cambridge University Press, Cambridge, England, 1993.