D.S. Anuradha, Kathavarayan.P. “Adriatic Indices of Periodic Porphyrin Nanostructure by Combinatorial Estimation”. International Journal of Advanced Science and Technology, Vol. 29, no. 9s, June 2020, pp. 6479 -85, http://sersc.org/journals/index.php/IJAST/article/view/20306.