@article{PORMA_1969__28_4_115098,
     author = {Yamada, Miyuki and Tamura, Takayuki},
     title = {Note on finite commutative nil-semigroups},
     journal = {Portugaliae mathematica},
     pages = {189--203},
     publisher = {mathdoc},
     volume = {28},
     number = {4},
     year = {1969},
     mrnumber = {0289698},
     zbl = {0214.03702},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1969__28_4_115098/}
}