H. Nazir, Syed Mazhar Ali Naqvi, Anam Ahmad, Saba Zartash, Ali Raza Khan, and Waqas Aslam, “Ultrasound Versus Bronchoscopy Guided Percutaneous Dilatational Tracheostomy: A Comparative Analysis”, PJMR, vol. 61, no. 4, pp. 173–178, Jan. 2023.