Siregar, F., Panggabean, G., Daulay, R., & Lubis, H. (2009). Comparison of peak expiratory flow rate (PEFR) before and after physical exercise in obese and non-obese children. Paediatrica Indonesiana, 49(1), 20-4. https://doi.org/10.14238/pi49.1.2009.20-4