Spence, D. P., Hay, J. G., Carter, J., Pearson, M. G., & Calverley, P. M. (1993). Oxygen desaturation and breathlessness during corridor walking in chronic obstructive pulmonary disease: Effect of oxitropium bromide.

Spence, D. P., J. G. Hay, J. Carter, M. G. Pearson, and P. M. Calverley. Oxygen Desaturation and Breathlessness During Corridor Walking in Chronic Obstructive Pulmonary Disease: Effect of Oxitropium Bromide. 1993.

Spence, D. P., et al. Oxygen Desaturation and Breathlessness During Corridor Walking in Chronic Obstructive Pulmonary Disease: Effect of Oxitropium Bromide. 1993.