@article{JRAM_1980__319_152287,
     author = {J\"urgen Hurrelbrink},
     title = {On {K2} (...) and presentations of {SLn} (...) in the real quadratic case.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {213--220},
     publisher = {mathdoc},
     volume = {319},
     year = {1980},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1980__319_152287/}
}