Richard Francis Burton: The Lake Regions of Central Africa. A Picture of Exploration. London 1859. Kapitel 14: Village Life in East Africa, S. 366f. Text Online (PDF; 31,2 MB)
fao.org
Mike Battcock, Sue Azam-Ali: Fermented Fruits and Vegetables. A Global Perspective. FAO Agricultural Services Bulletin, Nr. 134, 1998, Chapter 3. Yeast Fermentations. (beschreibt die Herstellung)