A prospective, randomized, double-masked comparison of a zonal-progressive multifocal intraocular lens and a monofocal intraocular lens. - Steinert ,R.F.; Post ,C.T.; Brint ,S.F.; Fritch ,C.D.; Hall ,D.L.; Wilder ,L.W.; Fine ,I.H.; Lichtenstein ,S.B.; Masket ,S.; Casebeer ,C.; Oksman ,H. (Ophthalmology, 1992)