@book{14588,
	author = {Shtokalo, I. Z.},
	title = {Linear differential equations with variable coefficients; criteria of stability and unstability of their solutions},
	publisher = {Hindustan},
	year = {1961},
	series = {International monographs on Advanced Mathematics and Physics},
	address = {Delhi},
	note = {"Tr. from the Russian".}
}