The expanded endonasal approach for an endoscopic transnasal clipping and aneurysmorrhaphy of a large vertebral artery aneurysm: technical case report - Kassam,A.B.; Mintz,A.H.; Gardner,P.A.; Horowitz,M.B.; Carrau,R.L.; Snyderman,C.H. (Neurosurgery, 2006)