@article{MOMA_1972__76_177591,
     author = {Josef P. Tschupik},
     title = {\"Uber die {Typen} der {A-Systeme.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {143--153},
     publisher = {mathdoc},
     volume = {76},
     year = {1972},
     zbl = {0236.50011},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1972__76_177591/}
}