@article{ASNSP_1933_2_2_1_21_0,
     author = {Haar, Alfred},
     title = {\"Uber die {Multiplikationstabelle} der unit\"ar-orthogonalen {Funktionensysteme}},
     journal = {Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche},
     pages = {21--40},
     publisher = {Scuola normale superiore},
     volume = {Ser. 2, 2},
     number = {1},
     year = {1933},
     zbl = {0006.20903},
     language = {de},
     url = {http://archive.numdam.org/item/ASNSP_1933_2_2_1_21_0/}
}