@article{PM_1989_1989_1_a9,
     author = {Fay, Temple H. and Hardie, Keith A. and Hilton, Peter J.},
     title = {Lema de los dos cuadrados.},
     journal = {Publicacions matem\`atiques},
     pages = {133-137},
     publisher = {mathdoc},
     volume = {33},
     number = {1},
     year = {1989},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PM_1989_1989_1_a9/}
}