@article{GDZPPN00206698X,
title = {A Riemann-Hurwitz formula for the Selmer group of an elliptic curve with complex multiplication.},
journal = {Commentarii mathematici Helvetici},
volume = {63},
year = {1988},
pages = {587-592},
zbl = {0682.12006},
url = {http://dml.mathdoc.fr/item/GDZPPN00206698X}
}
Wingberg, Kay. A Riemann-Hurwitz formula for the Selmer group of an elliptic curve with complex multiplication.. Commentarii mathematici Helvetici, Tome 63 (1988) pp. 587-592. http://gdmltest.u-ga.fr/item/GDZPPN00206698X/