@article{10_1017_S0017089500008168,
     author = {Fountain, John},
     title = {Free right type {A} semigroups},
     journal = {Glasgow mathematical journal},
     pages = {135--148},
     year = {1991},
     volume = {33},
     number = {2},
     doi = {10.1017/S0017089500008168},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500008168/}
}