@article{10_4153_CJM_1975_091_1,
     author = {Tomkinson, M. J.},
     title = {Prefrattini {Subgroups} and {Cover-Avoidance} {Properties} in {U-Groups}},
     journal = {Canadian journal of mathematics},
     pages = {837--851},
     year = {1975},
     volume = {27},
     number = {4},
     doi = {10.4153/CJM-1975-091-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1975-091-1/}
}