Progress in the Determination of the Gravitational Coefficient of the Earth (Paper 92GL00259) 529 . C. Ries, R. J. Eanes, C. K. Shum, and M. M. Watkins Accurate Determination of Cartesian Coordinates at Geodetic Stations Using the Global Positioning System (Paper 92GL00262) 533 Tomas Soler, William E. Strange, and Larry D. Hothem Sub-daily Resolution of Earth Rotation Variations With Global Positioning System Measurements (Paper 92GL00563) 537