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2. Current status of shade selection and color matching;Preston;Quintessence International,1985
3. Visual and instrumental colorimetric assessment of small color differences on translucent dental porcelain;Seghi;Journal of Dental Research,1989
4. Principles of color technology;Billmeyer,1981
5. A comparison of new and conventional methods for quantification of tooth color;Van der Burgt;Journal of Prosthetic Dentistry,1990