1. K.M. Allen, L.H. VanDyke, and R.L. Brunsbach, 1966 . Apparatus for detecting seeds in fruit. U.S. Patent No. 3,275,136.
2. Photomultiplier linearity
3. USDA., 1964 . United States Standards for Grades of Canned Red Tart Cherries. U.S. Dept. of Agriculture, ARS, mimeograph release dated June 15, 1964.