1. Clinical results of the multifocal lens;Keates;J Cataract Refract Surg,1987
2. Contrast sensitivity in patients with a new type of multifocal intraocular lens;Olsen;J Cataract Refract Surg,1990
3. The development and clinical performance of a new diffractive bifocal contact lens;Churms;Optometry Today,1987
4. A new diffractive bifocal contact lens;Freeman;Trans BCLA Conf,1987
5. Optics;Hecht;Addison Wesley World Student Series,1987