@article{CM_1987__63_2_271_0,
     author = {Cremona, J. E.},
     title = {Addendum and errata ``Hyperbolic tessellations, modular symbols, and elliptic curves over complex quadratic fields''},
     journal = {Compositio Mathematica},
     pages = {271--272},
     publisher = {Martinus Nijhoff Publishers},
     volume = {63},
     number = {2},
     year = {1987},
     zbl = {0626.14026},
     mrnumber = {906375},
     language = {en},
     url = {www.numdam.org/item/CM_1987__63_2_271_0/}
}

Cremona, J. E. Addendum and errata “Hyperbolic tessellations, modular symbols, and elliptic curves over complex quadratic fields”. Compositio Mathematica, Tome 63 (1987) no. 2, pp. 271-272. http://www.numdam.org/item/CM_1987__63_2_271_0/