Krishna Mohan, S., Tanu Srivastava, and K.V. Govindarajan. 2011. “Development of Foam Indicator Based on Cationic Surfactant Quaternized Fatty Acid Triethanolamine Ester”. Asian Journal of Chemistry 23 (6):2688-90. https://asianpubs.org/index.php/ajchem/article/view/10434.