1. Point-connected rigid bodies in a topological tree
2. 5Jerkovsky, W. "The Transformation Operator Approach to Multi-Body Dynamics," Aerospace Corp., El Segundo, Calif., Rept. TR-0076(6901-03)-5,1976; also The Matrix and Tensor Quarterly, Part 1 in Vol.27, Dec. 1976, pp.48-59; Part2 in Vol. 27, June 1977, pp. 116-128; Part 3 to be published.