@article{GDZPPN002312549, title = {A Commutativity Theorem for Hermitian Operators.}, journal = {Mathematische Annalen}, volume = {219}, year = {1976}, pages = {215-218}, zbl = {0305.47014}, url = {http://dml.mathdoc.fr/item/GDZPPN002312549} }
Dowson, H.R.; Gillespie, T.A.; Spain, P.G. A Commutativity Theorem for Hermitian Operators.. Mathematische Annalen, Tome 219 (1976) pp. 215-218. http://gdmltest.u-ga.fr/item/GDZPPN002312549/