Zahid Ullah, Muhammad, Shahkar A. Shah, Zahoor A. Khan, and Khalid Irshad. 2011. “Transthoracic Heller’s Myotomy for Achalasia of Cardia Experience With 28 Patients”. Journal of Postgraduate Medical Institute 12 (1). https://www.jpmi.org.pk/index.php/jpmi/article/view/601.