Mathematics
Mathematics
VOLKOVYSKII, L.I.;LUNTS, G.L.;ARAMANOVICH, I.G.
A Collection of Problems on Co..New York, Dover Publ., 1991.
JEFFREYS, HAROLD and BERTHA SWIRLES.
Methods of Mathematical Physic..Cambridge, University Press, 1956.
RITGER, PAUL D. and NICHOLAS J. ROSE.
Differential Equations with Ap..N.Y., Dover Publications, (2000).