1. When ellipsoidal heights will do the job, then why not use them;Kumar M.;Coordinates,2005
2. When ellipsoidal heights will do the job, why look elsewhere;Kumar M.;Surv. Land Inf. Sci.,2005
3. Ellipsoidal heights and engineering applications;Kumar M.;Coordinates,2006
4. Ellipsoidal heights: The future of vertical geodetic control;Steinberg G.;GPS World,1998
5. The height of reason;Vaníček P.;GPS World,1998