@article{10_1017_S2040618500034547,
     author = {Leech, John},
     title = {Some definitions of {Klein's} simple group of order 168 and other groups},
     journal = {Glasgow mathematical journal},
     pages = {166--175},
     year = {1962},
     volume = {5},
     number = {4},
     doi = {10.1017/S2040618500034547},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S2040618500034547/}
}