@article{PM_1992_1992_1_a3,
     author = {Varadarajan, Kalathoor},
     title = {Objetos hopfianos y co-hopfianos.},
     journal = {Publicacions matem\`atiques},
     pages = {293-317},
     year = {1992},
     volume = {36},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PM_1992_1992_1_a3/}
}