@article{SF_1982__24_134550,
     author = {T. Tamura},
     title = {Nil-orders of commutative nil-bounded semigroups.},
     journal = {Semigroup forum},
     pages = {255--262},
     publisher = {mathdoc},
     volume = {24},
     year = {1982},
     zbl = {0481.20037},
     url = {http://geodesic.mathdoc.fr/item/SF_1982__24_134550/}
}