Variational methods for eigenvalue problems : An introduction to the methods of Rayleigh, Ritz, Weinstein, and Aronszajn - Gould, Sydney H. 1909- (Dover Publications, 1995)
"An unabridged republication of the work originally published by the University of Toronto Press, Toronto, in 1957 as part of the Mathematical expositions series, no. 10"–T.p. verso.