1. Haugan, M.P., Will, C.M.: Phys. Today40 (5), 69 (1987)
2. Riis, E., Andersen, L.-U.,A., Bjerre, N., Poulsen, O., Siu, Au Lee, Hall, J.L.: Phys. Rev. Lett.60, 81 (1988); Poulsen, O., Bjerre, N., Riis, E., Siu Au Lee, Hall, J.L.: Atomic physics, vol. 11. Haroche, S., Gay, J.C., Grynberg, G. (eds.), p. 589. (Proc. 11th Int. Conf. on Atomic Physics.) Singapore: World Scientific 1989; see also Poulsen, O., Winstrup, N.I.: Phys. Rev. Lett.47, 1522 (1981); Kaivola, M., Poulsen, O., Riis, E., Siu Au Lee: Phys. Rev. Lett.54, 255 (1985)
3. Hils, D., Hall, J.L.: Phys. Rev. Lett.64, 1697 (1990) (modern Kennedy-Thorndike type experiment)
4. Krisher, T.P., Maleki, L., Lutes, G.F., Primas, L.E., Logan, R.T., Anderson, J.D., Will, C.M.: Phys. Rev. D42, 731 (1990) (experiment using the NASA Deep Space Network)
5. Huber, G., Schmidt, N., Schröder, S., Wendt, K., Dutta, M., Kühl, T., Marx, D., Orth, H.: Laser spectroscopy with stored relativistic7Li+ ions. Proposal for an Experiment at the ESR (GSI-ESR-111 (1988)); Henning, W.: Nucl. Phys. News1, 13 (1990)