Al-Mukhaini, N., T. Ba-Omar, E. A. Eltayeb, and A. A. Al-Shehi. “Analysis of Tobacco-Specific Nitrosamines in the Common Smokeless Tobacco Afzal in Oman”. Sultan Qaboos University Medical Journal, vol. 16, no. 1, Dec. 2020, pp. 20-26, doi:10.18295/squmj.2016.16.01.005.