@article{PORMA_1973__32_3_115203,
     author = {Rosenfeld, Azriel},
     title = {Chain semigroups},
     journal = {Portugaliae mathematica},
     pages = {155--156},
     publisher = {mathdoc},
     volume = {32},
     number = {3},
     year = {1973},
     mrnumber = {0316607},
     zbl = {0259.20058},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1973__32_3_115203/}
}