Information on Dr. Luther Emmett Holt's book Care and feeding of Children, published 1894, taken from: Mendelsohn, Dr. Robert, How to Raise a Healthy Child in Spite of Your Doctor, Contemporary Books, Inc., Chicago, 1984. (pp. 60-61)
Also referred to in the text on studies done on comforting children:
Blehar, Mary, Development of Mental Health in Infancy, National Institute of Mental Health, Science Monograph #3, U.S. Department of Health and Human Services, Washington DC 1980. (see pg. 39 for long-term effects of non-comforting on later ability of children to form close emotional relationships and have empathy)
Dunn, Judy, Distress and Comfort, in the Developing Child Series, Harvard University Press, Cambridge, MA, 1977.
Sears, William, The Fussy Baby, La Leche League International, Franklin Park, I11. 1985.