@article{IM_1991__104_1_143886,
     author = {James L. Heitsch and Connor Lazarov},
     title = {Homotopy invariance of foliation {Betti} numbers.},
     journal = {Inventiones mathematicae},
     pages = {321--348},
     publisher = {mathdoc},
     volume = {104},
     number = {1},
     year = {1991},
     zbl = {0756.46040},
     url = {http://geodesic.mathdoc.fr/item/IM_1991__104_1_143886/}
}