Analysing expenditure of same-day visitors in cave tourism: the case of Turkey / Hasan Akca, Murat Sayili and Reyhan Cafri
Grutas : Costa de Prata / Região de Turismo de Leiria
Ocio : campismo, montanhismo, turismo / dir. P. Cabrita
Les zones d'ombre du tourisme souterrain / Marc Duez