1. Westfall, R. S. (1980): Never at Rest: A biography of Isaac Newton. Cambridge Univ. Press, Cambridge.
2. Alberti, L. B. (1435): Delia pittora. Firenze. [Translated by J. R. Spenser (1967); On Painting, Yale University Press, New Haven.]
3. Maurolico, F. (1553): Photismi de Lumine et Umbrae ad Perspectivam et Radiorum Incidentiam Facientes. Venice. [Translated by H. Crew. (1940): Photismi de Lumine of Maurolico. A Chapter in Late Mediaeval Optics. American Book Company, New York.]
4. Kepler, J. (1611): Dioptrice. Prague. (Reprinted 1962, Cambridge University Press, Cambridge.)
5. Dominis, M. A. (1611): De Radüs Visus et Lueis in Vitris Perspeetivis et Iride Traetatus. Venice. [Summary in C. B. Boyer. (1959): The Rainbow, from Myth to Mathematics. Yoseloff Press. New York.]