1. Villar, E., Fernández, P. L., Quindós, L. S., Solana, J. R. & Soto, J. Trans. Br. Cave Res. Ass. 10, 65–70 (1983).
2. Bonet, A. et al. Trans. Br. Cave Res. Ass. 11, 92–97 (1984).
3. Fernández, P. L., Quindós, L. S., Soto, J. & Villar, E. Hlth Phys. 46, 445–448 (1984).
4. Wilkening, M. H. & Watkins, D. E. Hlth Phys. 31, 139–146 (1976).
5. Villar, E., Fernández, P. L., Quindós, L. S., Solana, J. R. & Soto, J. Trans. Br. Cave Res. Ass. 11, 99–105 (1984).