1. Incidence, prevalence, and mortality: intra-and inter-country differences;Higgins,1990
2. y Comité Científico del Estudio Iberpoc. Iberpoc: valoración de resultados;Villasante;Arch Bronconeumol,1999
3. Terminology, definitions and classification of chronic pulmonary emphysema and related conditions;Thorax,1959
4. Optimal assessment and management of chronic obstructive pulmonary disease (COPD). ERS Consensus statement;Siafakas;Eur Respir J,1995
5. Standards for the diagnosis and care of patients with chronic obstructive pulmonary disease. Official statement of the American Thoracic Society;Celli;Am J Respir Crit Care Med,1995