%0 Journal Article %A Brown, R. C. %A Hinton, D. B. %T Two separation criteria for second order ordinary or partial differential operators %J Mathematica Bohemica %D 1999 %P 273-292 %V 124 %N 2-3 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.21136/MB.1999.126251/ %R 10.21136/MB.1999.126251 %G en %F 10_21136_MB_1999_126251