@article{GDZPPN001174118, title = {Approximation in Variationally Posed Eigenvalue Problems.}, journal = {Numerische Mathematik}, volume = {28}, year = {1977}, pages = {159-172}, zbl = {0352.65059}, url = {http://dml.mathdoc.fr/item/GDZPPN001174118} }
Kolata, W.G. Approximation in Variationally Posed Eigenvalue Problems.. Numerische Mathematik, Tome 28 (1977) pp. 159-172. http://gdmltest.u-ga.fr/item/GDZPPN001174118/