1. N.U. AHMED, Properties of relaxed trajectories for a class of nonlinear evolution equations in a Banach space, SIAM J. Control and Optimization 21 (1983), 953–967.
2. J. DIEUDONNÉ, Sur le théoréme de Lebesgue-Nikodym (III), Ann. Université Grenoble 23 (1947–48), 25–53.
3. J. DIEUDONNÉ, Sur le théoréme de Lebesgue-Nikodym (IV), J. Indian Math. Soc. 22 (1951), 77–86.
4. N. DUNFORD AND J. T. SCHWARTZ, Linear Operators, part 1, Interscience, New York, 1958.
5. I. EKELAND, Nonconvex minimization problems, Bull. Amer. Math. Soc. 1 (NS) (1979), 443–474.