@article{1102912808,
author = {Lewis, Roger T.},
title = {Oscillation and nonoscillation criteria for some self-adjoint even order linear differential operators.},
journal = {Pacific J. Math.},
volume = {55},
number = {2},
year = {1974},
pages = { 221-234},
language = {en},
url = {http://dml.mathdoc.fr/item/1102912808}
}
Lewis, Roger T. Oscillation and nonoscillation criteria for some self-adjoint even order linear differential operators.. Pacific J. Math., Tome 55 (1974) no. 2, pp. 221-234. http://gdmltest.u-ga.fr/item/1102912808/