1. Agricultural Research Service. 1971. Lactation averages by breed and year for Official DHI cows calving from 1954 through 1968. Dairy Herd Improvement Letter, ARS 44-225. U.S. Dep. Agr.
2. Agricultural Research Service. 1972. State and national lactation averages by breed for Official DHI cows calving in 1969. Dairy Herd Improvement Letter, ARS 44-239. U.S. Dep. Agr.
3. Kendrick, J. F. 1955. Standardizing Dairy Herd Improvement Association records in proving sires. ARS 52-1. U.S. Dep. Agr.
4. Milk and fat differences for registered cows sired by artificial and natural insemination;McDaniel;J. Dairy Sci.,1974
5. McDaniel, B. T., R. H. Miller, and E. L. Corley. 1965. DHIA factors for projecting incomplete records to 305 days. August 1965 Dairy Herd Improvement Letter, ARS 44-164. U.S. Dep. Agr.