Instant aid. V.5. Part2 Differential equations of higher orders izd.3 / AntiDemidovich. T.5. Ch.2 Differentsialnye uravneniya vysshikh poryadkov, sistemy differentsialnykh uravneniy, uravneniya v chastnykh proizvodnykh pervogo poryadka. Spravochnoe posobie po vysshey matematike. Differentsialnye uravneniya v primerakh i zadachakh