1. Adamek, Z. and Rauser, J.: 1977, Studia Geographica Brno 62, 93.
2. Aley, T.: 1977, ‘A Model for Relating Land Use and Groundwater Quality in Southern Missouri’, in R. R. Dilamarter and S. C. Csallany (eds.), Hydraulic Problems in Karst regions, Proc. Symp. Western Kentucky Univ., Bowling Green, 232.
3. Apel, R.: 1971, Geologica Bavaria 64, 268.
4. Ashton, K.: 1968, Transactions Cave Research Group Great Britain 7, 161.
5. Atkinson, T. C.: 1971, Proc. Spelaology Soc. Univ. Bristol 12, 281.