@article{RRACEFN_1999_1999_1_a9,
     author = {JOS\'E F. PRIDA},
     title = {A nonstandard approach to arithmetic.},
     journal = {Revista de la Real Academia de Ciencias Exactas, F{\'\i}sicas y Naturales},
     pages = {227-229},
     year = {1999},
     volume = {93},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RRACEFN_1999_1999_1_a9/}
}