@article{1077376852,
author = {Krall, Allan M.},
title = {On the expansion problem for nonself-adjoint ordinary differential
operators of second order},
journal = {Duke Math. J.},
volume = {34},
number = {1},
year = {1967},
pages = { 163-174},
language = {en},
url = {http://dml.mathdoc.fr/item/1077376852}
}
Krall, Allan M. On the expansion problem for nonself-adjoint ordinary differential
operators of second order. Duke Math. J., Tome 34 (1967) no. 1, pp. 163-174. http://gdmltest.u-ga.fr/item/1077376852/