@article{10_2140_agt_2006_6_1957,
     author = {Pervova, Ekaterina and Petronio, Carlo},
     title = {On the existence of branched coverings between surfaces with prescribed branch data, {I}},
     journal = {Algebraic and Geometric Topology},
     pages = {1957--1985},
     year = {2006},
     volume = {6},
     number = {4},
     doi = {10.2140/agt.2006.6.1957},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2006.6.1957/}
}