Saxena, Jalaj, Sushma Gupta, and Sonali Saxena. 2006. “‘A Study of Change of Posture on the Pulmonary Function Tests : Can It Help Copd Patients ?’”. Indian Journal of Community Health 18 (1):10-12. https://www.iapsmupuk.org/journal/index.php/IJCH/article/view/108.