1. GPS Satellite Surveys and Vertical Control;Zilkosk;Journal of Surveying Engineering,1989
2. Orthometric Height Determination by GPS;Liddle;Surveying and Mapping,1989
3. Obtaining Centimeter-Precision Heights by GPS Observations Over Small Areas;Hajela;GPS World,1990
4. Orthometric Heights from Global Positioning System;Fiedler;Journal of Surveying Engineering,1992
5. Converting GPS Heights into NAVD98 Elevation with GEOID96 Geoid Height Model;Milbert,1996