-
https://static.caves.cz/data/media-manager/attachments/rocenka/rocenka-2015-web.pdf
Barbora Simeckova -
http://www.darswin.com/dw/Journals/ijg/Volume-3-2.htm
Preface -
Svilen Topchiev
- Traveling school of karst - new form for Lifelong Learning
- Celojosa vasaras skola Bulgarija
- UNESCO – Forderpreis fur Schulprojekt auf dem Karstwanderweg