Kaniakumari, Devi, and T.V. Rajendiran. “Synthesis and Characterization of New Azopolyimides Derived from Azobenzene Tetracarboxylic Dianhydride”. Asian Journal of Chemistry, vol. 21, no. 2, Mar. 2010, pp. 1097-06, https://asianpubs.org/index.php/ajchem/article/view/18795.