@article{10_4171_dm_155,
     author = {Serge Yagunov},
     title = {Rigidity {II:} non-orientable case},
     journal = {Documenta mathematica},
     pages = {29--40},
     year = {2004},
     volume = {9},
     doi = {10.4171/dm/155},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/155/}
}