@article{IM_1990__100_2_143776,
     author = {D.W. Masser and G. W\"ustholz},
     title = {Estimating isogenies on elliptic curves.},
     journal = {Inventiones mathematicae},
     pages = {1--24},
     publisher = {mathdoc},
     volume = {100},
     number = {2},
     year = {1990},
     zbl = {0722.14027},
     url = {http://geodesic.mathdoc.fr/item/IM_1990__100_2_143776/}
}