@article{IM_1981__63_142794,
     author = {Hiroaki Terao},
     title = {Generalized {Exponents} of a {Free} {Arrangement} of {Hyperplanes} and {Shepherd-Todd-Brieskorn} {Formula.}},
     journal = {Inventiones mathematicae},
     pages = {159--180},
     publisher = {mathdoc},
     volume = {63},
     year = {1981},
     zbl = {0437.51002},
     url = {http://geodesic.mathdoc.fr/item/IM_1981__63_142794/}
}