On multiplicative systems
Compositio Mathematica, Tome 8 (1951), p. 76-80
@article{CM_1951__8__76_0,
     author = {Levitzki, Jakob},
     title = {On multiplicative systems},
     journal = {Compositio Mathematica},
     publisher = {Kraus Reprint},
     volume = {8},
     year = {1951},
     pages = {76-80},
     zbl = {0033.34801},
     mrnumber = {33799},
     language = {en},
     url = {http://www.numdam.org/item/CM_1951__8__76_0}
}
Levitzki, Jakob. On multiplicative systems. Compositio Mathematica, Tome 8 (1951) pp. 76-80. http://www.numdam.org/item/CM_1951__8__76_0/