@article{CMUC_1975_16_4_a11,
     author = {Gregor, Radovan},
     title = {On rich monoids},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {735--743},
     year = {1975},
     volume = {16},
     number = {4},
     mrnumber = {0387369},
     zbl = {0332.18003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1975_16_4_a11/}
}