Kassab, S., U. Sachdeva, N. Das, T. Al-Shaibani, and U. Nayar. “Cardiovascular Responses to Tonic Pain in REM Sleep-Deprived Rats Role of Melatonin and Beta Endorphin”. Sultan Qaboos University Medical Journal, vol. 6, no. 1, June 2006, pp. 51-56, https://journals.squ.edu.om/index.php/squmj/article/view/1257.