Alonso, M. R.; Ibáñez, M.

Anatomy and Function of the Penial Twin Papillae System of the Helicinae  (Gastropoda: Helicoidea: Helicidae) and Description of Two New, Small Hemicycla Species from the Laurel Forest of the Canary Islands 

. Zootaxa 2007, 1482, 1–23.