@article{10_4064_cm_33_2_175_187,
     author = {Richard E. Phillips and J. M. Plotkin},
     title = {On factor coverings of groups},
     journal = {Colloquium Mathematicum},
     pages = {175--187},
     publisher = {mathdoc},
     volume = {33},
     number = {2},
     year = {1975},
     doi = {10.4064/cm-33-2-175-187},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-33-2-175-187/}
}