@article{SD_1971-1972__25_2_A14_0,
     author = {Clifford, Alfred H.},
     title = {Extensions of ordered semigroups},
     journal = {S\'eminaire Dubreil. Alg\`ebre et th\'eorie des nombres},
     note = {talk:J14},
     pages = {J1--J2},
     publisher = {Secr\'etariat math\'ematique},
     volume = {25},
     number = {2},
     year = {1971-1972},
     mrnumber = {387452},
     zbl = {0317.06012},
     language = {en},
     url = {http://www.numdam.org/item/SD_1971-1972__25_2_A14_0/}
}