@article{GDZPPN00206457X,
title = {A remark on two dimensional periodic potentials.},
journal = {Commentarii mathematici Helvetici},
volume = {57},
year = {1982},
pages = {130-134},
zbl = {0539.35059},
url = {http://dml.mathdoc.fr/item/GDZPPN00206457X}
}
Trubowitz, E.; Dahlberg, B.E.J. A remark on two dimensional periodic potentials.. Commentarii mathematici Helvetici, Tome 57 (1982) pp. 130-134. http://gdmltest.u-ga.fr/item/GDZPPN00206457X/