%0 Journal Article %A Howe, A. %T Klein's Oscillation Theorem for Periodic Boundary Conditions %J Canadian journal of mathematics %D 1971 %P 699-703 %V 23 %N 4 %U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1971-078-8/ %R 10.4153/CJM-1971-078-8 %F 10_4153_CJM_1971_078_8