1. MODIFIED POISSON PROBABILITY LAW FOR POINT PATTERN MORE REGULAR THAN RANDOM1
2. R. O. Ewers(1966), "Bedding Plane Anastomoses and Their Relation to Cavern Passages," Nat. Speleo. Soc. Amer., Bull, 28 (3), 133-40.
3. D. C. Ford(1964), "Origin of Closed Depressions in the Central Mendip Hills," Abstracts of Papers, 20th Int. Geog. Cong., London, 105-6.
4. Plot-Less Tests of Interspecific Association