@article{MAN_1935__111_159786,
     author = {B.S. Madhava Rao},
     title = {Separable systems in classical and wave mechanics.},
     journal = {Mathematische Annalen},
     pages = {459--468},
     year = {1935},
     volume = {111},
     zbl = {0012.08906},
     url = {http://geodesic.mathdoc.fr/item/MAN_1935__111_159786/}
}