@article{10_21136_CMJ_1971_101056,
     author = {Sasaki, Morio and Tamura, Takayuki},
     title = {Positive rational semigroups and commutative power joined cancellative semigroups without idempotent},
     journal = {Czechoslovak Mathematical Journal},
     pages = {567--576},
     publisher = {mathdoc},
     volume = {21},
     number = {4},
     year = {1971},
     doi = {10.21136/CMJ.1971.101056},
     mrnumber = {0292981},
     zbl = {0238.20083},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1971.101056/}
}