@article{PORMA_1993__50_1_115808,
     author = {Almeida, Jorge and Azevedo, A.},
     title = {On regular implicit operations},
     journal = {Portugaliae mathematica},
     pages = {35--61},
     publisher = {mathdoc},
     volume = {50},
     number = {1},
     year = {1993},
     mrnumber = {1300585},
     zbl = {0802.20049},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1993__50_1_115808/}
}