Sudheesh Kumar, K. 2011. “Synthesis and Characterization of Polyurethanes of Isophorone Diisocyanate Containing Bis(azo) and Bis(o-Nitrobenzyl) Chromophores in the Main Chain”. Asian Journal of Chemistry 23 (6):2705-8. https://asianpubs.org/index.php/ajchem/article/view/10435.