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3. Koichi Asatani, Studies on Singular Perturbations of Optimal Control Systems with Applications to Nuclear Reactor Control (Institute of Atomic Energy, Kyoto University, Kyoto, 1974).
4. Mathematics in Science and Engineering;D. J. Bell,1975
5. Gilmer Blankenship and Susan Sachs, "Singularly perturbed linear stochastic ordinary differential equations", Proceedings of the 1977 Joint Automatic Control Conference, 1232–1237, 1977.