Tashkin, D. P., Martinez, F. J., Rodriguez-Roisin, R., Fogarty, C., Gotfried, M., Denenberg, M., Gottschlich, G., Donohue, J. F., Orevillo, C., Darken, P., St Rose, E., Strom, S., Fischer, T., Golden, M., & Reisner, C. (2016). a multicenter, randomized, double-blind dose-ranging study of glycopyrrolate/formoterol fumarate fixed-dose combination metered dose inhaler compared to the monocomponents and open-label tiotropium dry powder inhaler in patients with moderate-to-severe COPD. Respiratory medicine, 120, 16–24. http://access.bl.uk/ark:/81055/vdc_100038918035.0x00003d