@article{MZ_1977__155_172546,
     author = {Wilberd van der Kallen and M.R. Stein},
     title = {On the {Schur} {Multipliers} of {Steinberg} and {Chevalley} {Groups} over {Commutative} {Rings.}},
     journal = {Mathematische Zeitschrift},
     pages = {83--94},
     publisher = {mathdoc},
     volume = {155},
     year = {1977},
     zbl = {0339.18007},
     url = {http://geodesic.mathdoc.fr/item/MZ_1977__155_172546/}
}