Mohanty, T., M. Patro, J. Sahoo, B. K. Meher, M. Pattnaik, and J. K. Patra. “Effectiveness of Pneumococcal Vaccine in Patients With Chronic Obstructive Pulmonary Disease (COPD)”. International Journal of Research in Medical Sciences, vol. 6, no. 11, Oct. 2018, pp. 3698-04, doi:10.18203/2320-6012.ijrms20184433.