@article{ADM_2002_1_a6,
     author = {Volodymyr Nekrashevych},
     title = {Virtual endomorphisms of groups},
     journal = {Algebra and discrete mathematics},
     pages = {88--128},
     publisher = {mathdoc},
     number = {1},
     year = {2002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ADM_2002_1_a6/}
}