@article{RM_1992_47_4_a0,
     author = {I. M. Gel'fand and M. I. Graev and V. S. Retakh},
     title = {General hypergeometric systems of equations and series of hypergeometric type},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {1--88},
     publisher = {mathdoc},
     volume = {47},
     number = {4},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1992_47_4_a0/}
}