@article{TIO_1991_1991_1_a4,
     author = {Garc{\'\i}a Laguna, Juan},
     title = {Una generalizaci\'on de la caracterizaci\'on de puntos extremos.},
     journal = {Trabajos de investigaci\'on operativa},
     pages = {71-82},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1991},
     language = {es},
     url = {http://geodesic.mathdoc.fr/item/TIO_1991_1991_1_a4/}
}