@article{10_21136_CMJ_1978_101526,
     author = {Byrd, Richard D. and Lloyd, Justin T. and Mena, Roberto A. and Teller, J. Roger},
     title = {The lattice of solid $\sigma$-subgroups of a retractable group},
     journal = {Czechoslovak Mathematical Journal},
     pages = {189--199},
     publisher = {mathdoc},
     volume = {28},
     number = {2},
     year = {1978},
     doi = {10.21136/CMJ.1978.101526},
     mrnumber = {0480249},
     zbl = {0388.06013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1978.101526/}
}