Combining Global Geopotential Models, Digital Elevation Models, and GNSS/Leveling for Precise Local Geoid Determination in Some Mexico Urban Areas: Case Study. - Norberto Alcantar-Elizondo; Ramon Victorino Garcia-Lopez; Xochitl Guadalupe Torres-Carillo; Guadalupe Esteban Vazquez-Becerra (ISPRS Int. J. Geo Inf., 2021)