Sloan, L. L. (1977). Reading aids for the partially sighted: A systematic classification and procedure for prescribing. Williams & Wilkins.
Dyfyniad Arddull ChicagoSloan, Louise Littig. Reading Aids for the Partially Sighted: A Systematic Classification and Procedure for Prescribing. Baltimore: Williams & Wilkins, 1977.
Dyfyniad MLASloan, Louise Littig. Reading Aids for the Partially Sighted: A Systematic Classification and Procedure for Prescribing. Williams & Wilkins, 1977.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.