@article{IM_1976__33_142375,
     author = {Ronnie Lee and R.H. Szczarba},
     title = {On the {Homology} and {Cohomology} of {Congruence} {Subgroups.}},
     journal = {Inventiones mathematicae},
     pages = {15--54},
     publisher = {mathdoc},
     volume = {33},
     year = {1976},
     zbl = {0332.18015},
     url = {http://geodesic.mathdoc.fr/item/IM_1976__33_142375/}
}