@article{10_1017_S0017089500004912,
     author = {Snowden, Mary and Howie, J. M.},
     title = {Square roots in finite full transformation semigroups},
     journal = {Glasgow mathematical journal},
     pages = {137--149},
     year = {1982},
     volume = {23},
     number = {2},
     doi = {10.1017/S0017089500004912},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004912/}
}