Efficacy, tolerability, and effects on quality of life of inhaled salmeterol and oral theophylline in patients with mild-to-moderate chronic obstructive pulmonary disease - Di Lorenzo,G.; Morici,G.; Drago,A.; Pellitteri,M.E.; Mansueto,P.; Melluso,M.; Norrito,F.; Squassante,L.; Falsolo,A. (Clin Therapeutics, 1998)