ZIMMERMAN, TJ. Trabaculectomy vs. nonpenetrating trabeculectomy : A retrospective study of two procedures in phakic patients with glaucome. Ophthalmic Surg. 1984, 15, 734-740
STEGMANN, R. Viscocanalostomy for open-angle glaucoma in black African patients. J Cataract Refract Surg. 1999, 25, 316-322