@article{10_1017_S0017089500001683,
     author = {Preston, G. B.},
     title = {Any group is a maximal subgroup of the semigroup of binary relations on some set{\textdagger}},
     journal = {Glasgow mathematical journal},
     pages = {21--24},
     year = {1973},
     volume = {14},
     number = {1},
     doi = {10.1017/S0017089500001683},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500001683/}
}