K. . Ahmed, S. . Shaikh, R. . Rehman, and S. M. . Ali, “Frequency Of Awareness And Practice Of Stethoscope Hygiene With Regards To Guide Line Among Medical Students, Residents And Doctors In Karachi”, J. Bahria Univ. Med. Dent. Coll., vol. 8, no. 1, pp. 31–34, Mar. 2018.