@article{10_4064_cm_15_2_191_194,
     author = {W{\l}odzimierz Waliszewski},
     title = {On a generalization of the notion of a semi-group},
     journal = {Colloquium Mathematicum},
     pages = {191--194},
     publisher = {mathdoc},
     volume = {15},
     number = {2},
     year = {1966},
     doi = {10.4064/cm-15-2-191-194},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-15-2-191-194/}
}