Double photoionization of helium: a generalized Sturmian approach Juan M. Randazzo, Darío Mitnik, Gustavo Gasaneo, Lorenzo U. Ancarani and Flavio D. Colavecchia Eur. Phys. J. D, 69 8 (2015) 189 Published online: 04 August 2015 DOI: 10.1140/epjd/e2015-60113-9