U.S. Department of Labor, Bureau of Labor Statistics, Occupational Outlook Handbook, 2008-09 Edition <http://www.bls.gov/oco/ocos118.htm>
doi.org
Cummins, J. David (1977). "Economies of Scale in Independent Insurance Agencies". The Journal of Risk and Insurance. 44 (4): 539–553. doi:10.2307/251718. JSTOR251718.
Cummins, J. David (1977). "Economies of Scale in Independent Insurance Agencies". The Journal of Risk and Insurance. 44 (4): 539–553. doi:10.2307/251718. JSTOR251718.