Rashid, Muhammad, et al. “CHEST X-RAY FINDINGS AND TYPES OF FOREIGN BODIES IN PATIENTS PRESENTING WITH COMPLAINTS OF TRACHEOBRONCHIAL FOREIGN BODY ASPIRATION; A NINE-YEAR MULTI-CENTER PROSPECTIVE STUDY”. Pakistan Armed Forces Medical Journal, vol. 70, no. 4, Aug. 2020, pp. 956-61, https://pafmj.org/PAFMJ/article/view/5063.