https://www.researchgate.net/publication/379480052_An_Overview_of_Physiological_Basis_of_Exercise_Training_in_Pulmonary_Rehabilitation/link/660b80e2390c214cfd2fa3ce/download?_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InB1YmxpY2F0aW9uIiwicGFnZSI6InB1YmxpY2F0aW9uIn19