Espeleologia (1987) – 6 документални филми за изследвания в пещери от колегите в Португалия
CEAE-LPN - Espeleologia The underground environment is completely dark, but in this particularly irregular environment one can progress in narrow places where the body can barely pass, or in spaces where several 4 or 5-storey buildings could be aligned. So one of the additional problems for filming was lighting. A história da primeira série didática produzida em Portugal sobre o ensino e a prática da Espeleologia.
Източник: http://www.lpn-espeleo.org
