1. Blumenthal, L. M.: Theory and applications of distance geometry. Oxford. Clarendon Press 1953.
2. Hall, Jr., Marshall: In some aspects of analysis and probability. A survey of combinatorial analysis. New York: Wiley 1958.
3. Ryser, H. J.: Combinatorial mathematics. Carus Monograph No. 14. Math. Ass. America. New York: Wiley 1963.
4. Schoenberg, I. J.: On metric spaces arising from Euclidean spaces. Ann. of Math.38, 787?793 (1937).
5. Sobczyk, A.: Convex polygons. Proc. Am. Math. Soc.15, 438?446 (1964).