@article{IM_1985__79_143217,
     author = {J.T. Stafford},
     title = {Non-holonomic modules over {Weyl} algebras and enveloping algebras.},
     journal = {Inventiones mathematicae},
     pages = {619--638},
     publisher = {mathdoc},
     volume = {79},
     year = {1985},
     zbl = {0558.17011},
     url = {http://geodesic.mathdoc.fr/item/IM_1985__79_143217/}
}