@article{10_21136_MB_1999_126251,
     author = {Brown, R. C. and Hinton, D. B.},
     title = {Two separation criteria for second order ordinary or partial differential operators},
     journal = {Mathematica Bohemica},
     pages = {273--292},
     publisher = {mathdoc},
     volume = {124},
     number = {2-3},
     year = {1999},
     doi = {10.21136/MB.1999.126251},
     mrnumber = {1780697},
     zbl = {0937.34068},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/MB.1999.126251/}
}