1. Proc. 4th NAMRC Conf.;Tipnis,1976
2. J. C. Miller and R. E. DeVor, SAE Technical Paper 800487.
3. R. G. Kleins and C. L. Nachtigal, J. dynam. Systems Measmt Control97, 179–183.
4. R. G. Klein and C. L. Nachtigal, Trans. Am. Soc. mech. Engrs. Publication 72-WA AUT-19.
5. 1977 JACC Conference;Mitchell,1977