@article{03792823, title = {On the product of self-adjoint operators.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {5}, year = {1982}, pages = {813-816}, doi = {10.1155/S0161171282000751}, zbl = {0503.47018}, language = {en}, url = {http://dml.mathdoc.fr/item/03792823} }
Rehder, Wulf. On the product of self-adjoint operators.. International Journal of Mathematics and Mathematical Sciences, Tome 5 (1982) pp. 813-816. doi : 10.1155/S0161171282000751. http://gdmltest.u-ga.fr/item/03792823/