- William H. Ukers, All about Coffee, The Tea and Coffee Trade Journal Company, New York 1922
- Aaron P. Davis, Royal Botanic Gardens, Kew, “A high extinction threat for wild coffee could rattle the sector“, online resource
- Matthew Attokaran, Coffee, Natural Food Flavors and Colorants, Blackwell Publishing and Inst. of Food Technologists, 2011, p163-166. ISBN 978-0-813-82110-8
- Coffee Atlas of Ethiopia, Aaron P. Davis et al, Kew Publishing
- Emiliano Rodriguez Mega, Wild coffee species threatened by climate change and deforestation, Nature, Jan 16th 2019
- G. A. Wright et al, Caffeine in Floral Nectar Enhances a Pollinator’s Memory of Reward Science, 08 MAR 2013 : 1202-1204
See full list of Individual Species References.
Please also refer to the General Bibliography and Online Resources.