1. E. Sutton. “Histograms and the Zone System”. Illustrated Photography. Accessed at http://www.illustratedphotography.com/photography-tips/basic/contrast.
2. Statistics in Psychology;Howitt,2008
3. NetMBA. Internet Center for Management and Business Administration, Inc. The Histogram. Accessed at http://www.netmba.com/statistics/histogram/.
4. K. Arvind.M, B Santhakumari and K. Mahesh. J., “Identification of specific proteins in tomato by intact tissue MALDI-TOF-MS,”. Electronic Journal of Food and Plants Chemistry 3(1) 2008 10–13.
5. D.K.N.G. Pushpakumara and S.A. Harris, “Potential of RAPD markers for identification of fruit types of Artocarpus Heteropyllus Lam. (jackfruit),” J. Nat. Sci. Foundation Sri Lanka 2007, 35(3):175–179.