Cita APA (7a ed.)

Yu, T., Riet, G. t., Puhan, M. A., & Frei, A. (2017). Physical activity and risk of comorbidities in patients with chronic obstructive pulmonary disease: A cohort study. Nature Portfolio.

Cita Chicago Style (17a ed.)

Yu, Tsung, Gerben ter Riet, Milo A. Puhan, y Anja Frei. Physical Activity and Risk of Comorbidities in Patients with Chronic Obstructive Pulmonary Disease: A Cohort Study. Nature Portfolio, 2017.

Cita MLA (8a ed.)

Yu, Tsung, et al. Physical Activity and Risk of Comorbidities in Patients with Chronic Obstructive Pulmonary Disease: A Cohort Study. Nature Portfolio, 2017.