@article{IM_1982__66_142883,
     author = {Steven Hurder},
     title = {Independent {Rigid} {Secondary} {Classes} for {Holomorphic} {Foliations.}},
     journal = {Inventiones mathematicae},
     pages = {313--324},
     publisher = {mathdoc},
     volume = {66},
     year = {1982},
     zbl = {0489.57006},
     url = {http://geodesic.mathdoc.fr/item/IM_1982__66_142883/}
}