참고문헌
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- Trans. Amer. Math. Soc. v.215 Fixed point theorems for mapping satisfying inwardness conditions J.Caristi
- I. C. R. Acad. Sci. Paris ser. A-B v.275 Remarques sur les problems variationnels I.Ekeland
- Bull. Amer. Math. Soc. v.1 Nonconvex minimization problems I.Ekeland
- J. Math. Anal. Appl. v.83 Fuzzy mappings and fixed point theorem S.Heilpern
- Pacific J. Math. v.30 Multivalued contraction mappings S.B.Nadler,Jr.