M. Pitchford, W. Malm, B. Schichtel, N. Kumar, D. Lowenthal and J. Hand, “Revised Algorithm for Estimating Light Extinction from IMPROVE Particle Speciation Data,” Journal of the Air & Waste Management Association, Vol. 57, 2007, pp. 1326-1336. doi:10.3155/1047-32126.96.36.1996
 National Institute of Science and Technology, “e-Handbook of Statistical Methods,” 5 July 2010. http://www.itl.nist.gov/div898/handbook/
 P. A. Ryan, D. Lowenthal and N. Kumar, “Improved Light Extinction Reconstruction in Interagency Monitoring of Protected Visual Environments,” Journal of the Air & Waste Management Association, Vol. 55, 2005, pp. 1751-1759.
 J. Rokjin, D. Jacoba, N. Kumar and R. Yantoscaa, “Regional Visibility Statistics in the United States: Natural and Transboundary Pollution Influences, and Implications for the Regional Haze Rule,” Atmospheric Environment, Vol. 40, No. 28, 2006, pp. 5405-5423. doi:10.1016/j.atmosenv.2006.04.059
 C. Heald, D. Jacob, R. Park, B. Alexander, T. Fairlie, R. Yantosca and D. Chu, “Transpacific Transport of Asian Anthropogenic Aerosols and Its Impact on Surface Air Quality in the United States,” Journal of Geophysical Research, Vol. 111, 2007, Article ID: D14310.