Erugin, Nikolay P. Linear systems of ordinary diffential equations with periodic and quasi-periodic coefficients - New York : Academic Press, 1966 - 271 p. - Mathematics in science and enginering ; 28 . - Mathematics in science and enginering ; 28 . LCCN: 41696 Subjects--Topical Terms: Ecuaciones diferenciales. Dewey Class. No.: 517.38 / E7Y