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@article{MOMA_1974__78_186323, author = {Elbert M. Pirtle}, title = {A {Generalization} of the {Class} {Group.}}, journal = {Monatshefte f\"ur Mathematik}, pages = {237--245}, publisher = {mathdoc}, volume = {78}, year = {1974}, zbl = {0289.13008}, url = {http://geodesic.mathdoc.fr/item/MOMA_1974__78_186323/} }
Elbert M. Pirtle. A Generalization of the Class Group.. Monatshefte für Mathematik, Tome 78 (1974), pp. 237-245. http://geodesic.mathdoc.fr/item/MOMA_1974__78_186323/