@article{10_4171_ggd_441,
     author = {Laurent Bartholdi and Dzmitry Dudko},
     title = {Algorithmic aspects of branched coverings {I/V.} {Van} {Kampen{\textquoteright}s} theorem for bisets},
     journal = {Groups, geometry, and dynamics},
     pages = {121--172},
     year = {2018},
     volume = {12},
     number = {1},
     doi = {10.4171/ggd/441},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/ggd/441/}
}