@article{BUMI_1960_3_15_3_a4,
     author = {Putnam, C. R.},
     title = {On the spectra of group commutators.},
     journal = {Bollettino della Unione matematica italiana},
     pages = {379--383},
     year = {1960},
     volume = {Ser. 3, 15},
     number = {3},
     zbl = {0098.30801},
     mrnumber = {124746},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BUMI_1960_3_15_3_a4/}
}