@article{MAN_1990__288_1_164729,
     author = {E. Colombo and G.P. Pirola},
     title = {Some density results for curves with non-simple jacobians.},
     journal = {Mathematische Annalen},
     pages = {161--178},
     publisher = {mathdoc},
     volume = {288},
     number = {1},
     year = {1990},
     zbl = {0716.14015},
     url = {http://geodesic.mathdoc.fr/item/MAN_1990__288_1_164729/}
}