1. World Populationhttps://en.wikipedia.org/wiki/World_population
2. Foreword;Buffet,2017
3. Asia Populationhttp://www.worldometers.info/world-population/asia-population/
4. Global Assessment of Human-Induced Soil Degradation (GLASOD)http://www.isric.org/projects/global-assessment-human-induced-soil-degradation-glasod
5. Soil Atlas of Africa;Jones,2013