@article{PORMA_1981__40_3_115451,
     author = {Basto Gon\c{c}alves, J.},
     title = {Equival\^encia de sistemas de gradiente},
     journal = {Portugaliae mathematica},
     pages = {263--277},
     publisher = {mathdoc},
     volume = {40},
     number = {3},
     year = {1981},
     mrnumber = {0819891},
     zbl = {0562.93042},
     language = {es},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1981__40_3_115451/}
}