@article{RMI_1991_1991_1_a2,
     author = {Lewis, John L. and Vogel, Andrew},
     title = {Pseudoesferas.},
     journal = {Revista matem\'atica iberoamericana},
     pages = {25-54},
     year = {1991},
     volume = {7},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RMI_1991_1991_1_a2/}
}