Rehman, A., H. Zeb, and A. U. K. Niazi. “Ultrasound Guidance Increases the Safety and Ease of Insertion of Central Venous Catheters in Patients Undergoing Elective Procedures”. Anaesthesia, Pain & Intensive Care, Jan. 2019, pp. 474-7, https://apicareonline.com/index.php/APIC/article/view/285.