1. A. T. Balaban, D. Farcasiu, and R. Banica Rev. Roum. Chim. 1966, 11, 1205
2. C. J. Collins, C. K. Johnson, and V. F. Raaen J. Amer. Chem. Soc. 1974, 96, 2524.
3. M. Gielen, in Chemical Applications of Graph Theory (A.T. Balaban, ed.), Academic Press, London, 1976, p. 261.
4. J. Brocas, M. Gielen, and R. Willem, The Permutational Approach to Dynamic Stereochemistry, McGraw-Hill, New York,1983.
5. T. M. Gund, P. v. R. Schleyer, P. H. Gund, and W. T. Wipke J. Amer. Chem. Soc. 1975, 97, 743.