1. American Druggist Blue Book 1973 The American Druggist March 1973
2. Cooper , Barbara S. Nancy L. Worthington National Health Expenditures, Calendar Years 19291970 Research and Statistics Bulletin No. 1
3. Dixon , Donald F. Daniel J. McLaughlin , Jr. Do the Inner City Poor Pay More for Food Economics and Business Bulletin 1969 6 12
4. Predicting Prescription Prices;Hastings;The New England Journal of Medicine,September 1967