1. The saga of lambda: spectral influences throughout lithography generations;Smith,2012
2. The Influence of the Condenser on Microscopic Resolution;Hopkins,1950
3. Wolf, E. and Born, M., Principles of Optics, Pergamon Press, New York, 522–525, (1959).
4. Contributions to the Theory of Microscopes;Abbe,1874
5. Stephensen, J.W., Monthly Miscrosc. Journ, 17, p. 83, (1878).