1. K Mislow,Introduction to stereochemistry (Benjamin, New York, 1965)
2. G Schill,Catenanes, rotaxanes, and knots (Academic, New York, 1971)
3. D M Walba,Tetrahedron 41, 3161 (1985);Catenanes, rotaxanes and knots edited by J-P Sauvage and C Dietrich-Buchecker (VCH, Weilheim, 1999)
4. H L Frisch and E Wassermann,J. Am. Chem. Soc. 83, 3789 (1961)
5. M Delbrück, inMathematical problems in biological sciences edited by R E Bellman,Proc. Symp. Appl. Math., vol. 14, p. 55