Gustomesov, V. A.; Danilin, A. R. Differential equations. Textbook. (Differentsial’nye uravneniya. Uchebnoe posobie.) (Russian) Zbl 0773.34002 Sverdlovsk: Sverdlovskij Gosudarstvennyj Pedagogicheskij Institut, 88 p. (1990). Reviewer: Yu.V.Rogovchenko (Kiev) MSC: 34-01