In this paper we classify all Riemann surfaces having a large abelian group of automorphisms, that is having an abelian group of automorphism of order strictly bigger then 4(g-1), where g denotes as usual the genus of the Riemann surface.
@article{urn:eudml:doc:41773, title = {Riemann surfaces with a large abelian group of automorphisms.}, journal = {Collectanea Mathematica}, volume = {57}, year = {2006}, pages = {309-318}, zbl = {1109.14027}, mrnumber = {MR2264325}, language = {en}, url = {http://dml.mathdoc.fr/item/urn:eudml:doc:41773} }
Lomuto, Clelia. Riemann surfaces with a large abelian group of automorphisms.. Collectanea Mathematica, Tome 57 (2006) pp. 309-318. http://gdmltest.u-ga.fr/item/urn:eudml:doc:41773/