Hartridge, G. (1898). The refraction of the eye: A manual for students (9th ed.). J. & A. Churchill.
Lua i Stíl Chicago (17ú heag.)Hartridge, Gustavus. The Refraction of the Eye: A Manual for Students. 9th ed. London: J. & A. Churchill, 1898.
Lua MLA (8ú heag.)Hartridge, Gustavus. The Refraction of the Eye: A Manual for Students. 9th ed. J. & A. Churchill, 1898.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.