1. Walgate, R. Nature 305, 665 (1983).
2. Wahlquist, H. D., Anderson, J. D., Estabrook, F. B. & Thorne, K. S. Atti Conv. Lincei 34, 335–350 (1977).
3. Estabrook, F. B., Hellings, R. W., Wahlquist, H. D. & Wolff, R. S. in Sources of Gravitational Radiation (ed. Smarr, L.) 37–48 (Cambridge University Press, London and New York, 1979).
4. Anderson, J. D., Armstrong, J. W. & Estabrook, F. B. in Proc. 13th A. Precise Time and Time Interval (PTTI) Applications and Planning Meet., 757–766 (NASA Conf. Publ. 2220, 1982).
5. Estabrook, F. B. & Wahlquist, H. D. Gen. Relativity Gravitation 6, 439–447 (1975).