1. Corneal topography and its role in refractive surgery;Naroo,2004
2. Novo instrumento per analyse immediate das irregularitades de curvatura da cornea;Placido;Periodico Oftalmol Practica,1880
3. The true inventors of the keratoscope and photo-keratoscope;Levene;Br J Hist Sci,1965
4. Photographic-ophthalmometric and clinical investigations of corneal refraction;Gullstrand;Am J Optom Arch Am Acad Optom,1966
5. Corneal contour of the human infant;Mandell;Arch Ophthalmol,1967