Journal Article
                        
                        Caballero, Andres, Carlos A Torres-Duque, Claudia  Jaramillo, Fabio  Bolivar, Fernando  Sanabria, Patricia  Osorio, Carlos  Orduz, Diana P Guevara, and Dari´o  Maldonado.  
"Prevalence of COPD in five Colombian cities situated at low, medium, and high altitude (PREPOCOL study)." CHEST Journal 133, no. 2 (2008): 343-349.