@article{CMJ_2008_58_3_a5,
     author = {Gardner, B. J. and Parmenter, M. M.},
     title = {Directoid groups},
     journal = {Czechoslovak Mathematical Journal},
     pages = {669--681},
     year = {2008},
     volume = {58},
     number = {3},
     mrnumber = {2455929},
     zbl = {1174.06340},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMJ_2008_58_3_a5/}
}