@article{10_4171_dm_136,
     author = {Bas Edixhoven and Chandrashekhar Khare},
     title = {Hasse invariant and group cohomology},
     journal = {Documenta mathematica},
     pages = {43--50},
     year = {2003},
     volume = {8},
     doi = {10.4171/dm/136},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/136/}
}