@article{MZ_1982__180_173182,
     author = {Guido Van Steen},
     title = {Galois {Coverings} of the {Non-Archimedean} {Projective} {Line.}},
     journal = {Mathematische Zeitschrift},
     pages = {217--224},
     year = {1982},
     volume = {180},
     zbl = {0471.14010},
     url = {http://geodesic.mathdoc.fr/item/MZ_1982__180_173182/}
}