@article{10_1017_S0017089500005668,
     author = {Trotter, P. G.},
     title = {Free completely regular semigroups},
     journal = {Glasgow mathematical journal},
     pages = {241--254},
     year = {1984},
     volume = {25},
     number = {2},
     doi = {10.1017/S0017089500005668},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500005668/}
}