@article{10_4153_CMB_1986_053_2,
     author = {Higgins, Peter M.},
     title = {A {Method} for {Constructing} {Square} {Roots} in {Finite} {Full} {Transformation} {Semigroups}},
     journal = {Canadian mathematical bulletin},
     pages = {344--351},
     year = {1986},
     volume = {29},
     number = {3},
     doi = {10.4153/CMB-1986-053-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1986-053-2/}
}