Nouwen, M. J., E. J. B. Helmich, D. H. T. Tjan, and M. S. . van der Steen. “Side Stream End-Tidal CO2 Monitoring in Subjects Undergoing Non-Invasive Ventilation for Respiratory Failure: A Pilot Study”. Global Journal of Respiratory Care, vol. 3, June 2016, pp. 1-9, doi:10.12974/2312-5470.2016.03.1.