@book{7980,
	author = {Encyclopaedia of Mathematical Sciences and Shubin, M. A.; ed.},
	title = {Partial differential equations; No.7 - Spectral theory of differential operators},
	publisher = {Springer-Verlag},
	year = {1994},
	series = {Encyclopaedia of Mathematical Sciences},
	address = {Berlin},
	note = {"Purchased under NBHM grant for the year 1994-1995"}
}