@article{IM_1972__17_142159,
     author = {Jan-Erik Bj\"ork},
     title = {The {Global} {Homological} {Dimension} of {Some} {Algebras} of {Differential} {Operators.}},
     journal = {Inventiones mathematicae},
     pages = {67--78},
     year = {1972},
     volume = {17},
     zbl = {0241.12107},
     url = {http://geodesic.mathdoc.fr/item/IM_1972__17_142159/}
}