1. H. L. Kempster. “Length of Period Required to Reach Maturity as an Indication of Future Egg Production.” Missouri Agricultural Extension Experiment, Bulletin No. 189, p. 48.
2. “Early Maturing versus Late Maturing White Leghorn Pullets.”;Kennard;Monthly Bulletin Ohio Experiment Station, November-December,1921
3. “Length of Period Required to Reach Maturity as an Indication of Future Egg Production;Kempster;December, Missouri Bulletin,1922