Knudsen, T. M., O. Morkve, S. Mfinanga, and J. Hardie. “Predictive Equations for Spirometric Reference Values in a Healthy Adult Suburban Population in Tanzania”. Tanzania Journal of Health Research, vol. 13, no. 3, July 2011, pp. 214-23, doi:10.4314/thrb.v13i3.64540.