1. The color problem in dentistry;Clark;Dent Digest,1931
2. The Clark tooth colour system;Clark;Den Mag and Oral Topics,1933
3. Tooth color selection;Clark;J Am Dent Assoc,1933
4. An analysis of tooth color;Clark;J Am Dent Assoc,1931
5. Color matching in dentistry. Part II. Practical applications of the organization of color;Sproull;J Prosthet Dent,1973