@article{JRAM_1996__470_153779,
     author = {Claus Michael Ringel},
     title = {PBW-bases of quantum groups.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {51--88},
     year = {1996},
     volume = {470},
     zbl = {0840.17010},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1996__470_153779/}
}