1. Forsythe, R. H., 1966. Modern marketing demands sound shells. Paper presented at Nebraska Egg Shell Quality Conference, March 23, 1966.
2. Toleman, W. J., T. H. Coleman and L. E. Dawson 1964. Factors affecting the number of cracked eggs produced on Michigan farms. Research Report 17, Michigan State University Agr. Exp. Sta., East Lansing, Michigan.