Thorax Maddocks, M, Kon, S S C, Canavan, J L, Jones, S E, Nolan, C M, Labey, A, Polkey, M I & Man, W D-C 2016, ' Physical frailty and pulmonary rehabilitation in COPD : a prospective cohort study ', Thorax, vol. 71, pp. 988–995 . https://doi.org/10.1136/thoraxjnl-2016-208460
New England Journal of Medicine, 377(19), 1836-1846. MASSACHUSETTS MEDICAL SOC New England journal of medicine, 377(19), 1836-1846. Massachussetts Medical Society New England Journal of Medicine, 377(19), 1836-1846. MASSACHUSETTS MEDICAL SOCIETY