@article{JRAM_1970__241_151006,
     author = {Norman L. Alling},
     title = {Real {Banach} algebras and nonorientable {Klein} surfaces. {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {200--208},
     publisher = {mathdoc},
     volume = {241},
     year = {1970},
     zbl = {0191.13703},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1970__241_151006/}
}