@article{1250126808,
author = {Everitt, W.N. and Zettl, Anton},
title = {Sturm-liouville differential operators in direct sum spaces},
journal = {Rocky Mountain J. Math.},
volume = {16},
number = {4},
year = {1986},
pages = { 497-516},
language = {en},
url = {http://dml.mathdoc.fr/item/1250126808}
}
Everitt, W.N.; Zettl, Anton. Sturm-liouville differential operators in direct sum spaces. Rocky Mountain J. Math., Tome 16 (1986) no. 4, pp. 497-516. http://gdmltest.u-ga.fr/item/1250126808/