@article{10_4153_CJM_1970_021_x,
     author = {Dark, Rex and Rhemtulla, Akbar H.},
     title = {On {R} {0-Closed} {Classes,} and {Finitely} {Generated} {Groups}},
     journal = {Canadian journal of mathematics},
     pages = {176--184},
     year = {1970},
     volume = {22},
     number = {1},
     doi = {10.4153/CJM-1970-021-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1970-021-x/}
}