1. Frick, I. (1977). University of Stockholm Institute of Theoretical Physics technical report 77-15.
2. Joly, G. C. (1986). InEleventh International Conference on General Relativity and Gravitation, Abstracts Vol. 1.
3. Hohnes, G. (1986). InEleventh International Conference on General Relativity and Gravitation, Abstracts Vol. 1.
4. Hörnfeldt, L. (1988).Computer Algebra in Relativity (Methods for handling abstract tensors and noncommutative objects), University of Stockholm Ph. D thesis.
5. Hearn, A. C. (1985).REDUCE Users Manual — Version 3.2, Rand Publication CP78 (Rev. 4/85), (The Rand Corporation, Santa Monica, California).