P. N. Khandelwal, S. H. Maaz, and D. M. Borade, “Evaluation of efficacy and safety of doxofylline 800mg sustained release tablet in treatment of patients with COPD: an open label, prospective and RCT”, Int J Basic Clin Pharmacol, vol. 7, no. 4, pp. 644–649, Mar. 2018.