Żaba, Jerzy, and Krzysztof Gaidzik. “The Ngorongoro Crater As the Biggest Geotouristic Attraction of the Gregory Rift (Northern Tanzania, Africa) – Geotouristic Valorization, Touristic Development and Hazard”. Geotourism/Geoturystyka, no. 24-25 ():47. https://doi.org/10.7494/geotour.2011.24-25.47.