@article{10_21136_MB_2009_140663,
     author = {Cegarra, Antonio M. and Petrich, Mario},
     title = {The rank of a commutative semigroup},
     journal = {Mathematica Bohemica},
     pages = {301--318},
     publisher = {mathdoc},
     volume = {134},
     number = {3},
     year = {2009},
     doi = {10.21136/MB.2009.140663},
     mrnumber = {2561308},
     zbl = {1197.20051},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/MB.2009.140663/}
}