@article{10_4064_cm_30_2_219_223,
     author = {J. Dudek},
     title = {A characterization of some idempotent abelian groupoids},
     journal = {Colloquium Mathematicum},
     pages = {219--223},
     publisher = {mathdoc},
     volume = {30},
     number = {2},
     year = {1974},
     doi = {10.4064/cm-30-2-219-223},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-30-2-219-223/}
}