Urwyler, Pascal, et al. “Predictive Factors for Exacerbation and Reexacerbation in Chronic Obstructive Pulmonary Disease: An Extension of the Cox Model to Analyze Data from the Swiss COPD Cohort”. Multidisciplinary Respiratory Medicine, vol. 14, no. 1, Feb. 2019, https://doi.org/10.4081/mrm.2019.6.