@article{10_4064_cm89_2_9,
     author = {Piotr Dowbor},
     title = {Non-orbicular modules {for
Galois} coverings},
     journal = {Colloquium Mathematicum},
     pages = {241--310},
     publisher = {mathdoc},
     volume = {89},
     number = {2},
     year = {2001},
     doi = {10.4064/cm89-2-9},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm89-2-9/}
}