1. Parameters that Affect the Color of Direct Restorative Resins
2. Reflectance spectra of composite resins on liners
3. Yeh, C.L.: The Color and Optical Properties of Shaded Composites. Master's thesis , University of Michigan, Ann Arbor, MI, 1981, 104 pp.
4. Wyszecki, G. and Stiles, W.S.: Color Science, New York, NY: Wiley & Sons, Inc., 1967,628 pp.
5. Opacity of Paper, D 589-65, 1970. In: ASTM Standards, Part 20, Philadelphia, PA: American Society for Testing & Materials, 1975, pp. 86-88.