00360nam a2200121Ia 4500082001700000100002200017245006400039260004800103300003300151490004400184500000500228700000500233  a516bG427.DP  aGhoussoub, Nassif  aDuality and perturbation methods in critical point theoryb  aCambridgebCambridge University Pressc1991  axviii, 258p. Index. Appendix  aCambridge tracts in Mathematicsv v.107  a  a