@article{GDZPPN002207907,
title = {The invertible elements are dense in the irrational rotation C*-algebras.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {405},
year = {1990},
pages = {160-166},
zbl = {0697.46027},
url = {http://dml.mathdoc.fr/item/GDZPPN002207907}
}
Putnam, Ian F. The invertible elements are dense in the irrational rotation C*-algebras.. Journal für die reine und angewandte Mathematik, Tome 405 (1990) pp. 160-166. http://gdmltest.u-ga.fr/item/GDZPPN002207907/