@article{10_1090_S0894_0347_1995_1303029_0,
     author = {Cuntz, Joachim and Quillen, Daniel},
     title = {Algebra extensions and nonsingularity},
     journal = {Journal of the American Mathematical Society},
     pages = {251--289},
     publisher = {mathdoc},
     volume = {08},
     number = {2},
     year = {1995},
     doi = {10.1090/S0894-0347-1995-1303029-0},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-1995-1303029-0/}
}