Bhattacharyya, A. K., A. K. Gupta, and H. S. Nayar. “New Low Resistance Respiratory Valve”. Defence Science Journal 32, no. 2 (February 12, 2014): 95–98. Accessed June 15, 2025. https://publications.drdo.gov.in/ojs/index.php/dsj/article/view/6199.