Validity and reliability of the St George's Respiratory Questionnaire after adaptation to a different language and culture: the Spanish example
M Ferrer, J Alonso, L Prieto, V Plaza, E Monso, R Marrades, MC Aguar, A Khalaf, JM Anto
European Respiratory Journal 1996 9: 1160-1166; DOI: 10.1183/09031936.96.09061160