@article{SF_1974__6_133961,
     author = {W.R. Nico},
     title = {A study of operands in terms of maximal generalized orbits.},
     journal = {Semigroup forum},
     pages = {69--74},
     publisher = {mathdoc},
     volume = {6},
     year = {1974},
     zbl = {0256.20092},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__6_133961/}
}