@article{SF_1978__16_134290,
     author = {F.W. Roush and K.H. Kim},
     title = {Orders of subsemigroups of {Tn.}},
     journal = {Semigroup forum},
     pages = {203--203},
     year = {1978},
     volume = {16},
     zbl = {0401.20061},
     url = {http://geodesic.mathdoc.fr/item/SF_1978__16_134290/}
}