@article{CMUC_1979__20_3_a10,
     author = {Luedeman, John K.},
     title = {Closure operations and semigroups of quotients},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {529--537},
     publisher = {mathdoc},
     volume = {20},
     number = {3},
     year = {1979},
     mrnumber = {550454},
     zbl = {0412.20062},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1979__20_3_a10/}
}