http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Linear systems of ordinary differential equations
with periodic and quasi-periodic coefficients, with revisions by the author for the English edition
[by] Nikolay P. Erugin. Translated by Scripta Technica. Translation editor: Richard Bellman.
Mathematics in science and engineering, v. 28