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@article{MV_1975_27_4_a3, author = {W. Hahn}, title = {\"Uber orthogonalit\"atserhaltende {Operatoren}}, journal = {Matemati\v{c}ki vesnik}, pages = {337 }, publisher = {mathdoc}, volume = {27}, number = {4}, year = {1975}, url = {http://geodesic.mathdoc.fr/item/MV_1975_27_4_a3/} }
W. Hahn. Über orthogonalitätserhaltende Operatoren. Matematički vesnik, Tome 27 (1975) no. 4, p. 337 . http://geodesic.mathdoc.fr/item/MV_1975_27_4_a3/