SINGH, SUKHPAL, ASHOK KUMAR, JARNAIL SINGH, KULWANT SINGH THIND, and GURMEL S. MUDAHAR. 2010. “Mass Attenuation Coefficients Studies in Some Flyash Materials”. Asian Journal of Chemistry 18 (5):3314-16. https://asianpubs.org/index.php/ajchem/article/view/13849.