Kronborg, M., J.-B. Ilboudo, I. H. N. Bassolé, A. S. Barfod, H. W. Ravn, and A. M. Lykke. “Correlates of Product Quality of Soumbala, a West African Non-Timber Forest Product”. Ethnobotany Research and Applications, vol. 12, Mar. 2014, pp. 025-37, https://ethnobotanyjournal.org/index.php/era/article/view/785.