1. Newsome, D., and Dowling, R.K. (2010). Geotourism: The Tourism of Geology and Landscape, Goodfellow Publishers.
2. Kurek, W., Faracik, R., Mika, M., Pawlusiński, W., Pitrus, E., and Ptaszycka-Jackowska, D. (2007). Turystyka, Wydawnictwo Naukowe PWN.
3. Dowling, R., and Newsome, D. (1995). Geotourism, Butterworth Heinemann; Elsevier Science.
4. Geotourism’s Global Growth;Dowling;Geoheritage,2011
5. Geosites within Rome city center (Italy): A mixture of cultural and geomorphological heritage;Fredi;Geogr. Fis. Din. Quat.,2013