@article{MZ_1964__85_170314,
     author = {James Wiegold and Peter M. Neumann},
     title = {Schreier varieties of groups.},
     journal = {Mathematische Zeitschrift},
     pages = {392--400},
     publisher = {mathdoc},
     volume = {85},
     year = {1964},
     zbl = {0126.26901},
     url = {http://geodesic.mathdoc.fr/item/MZ_1964__85_170314/}
}