European Space Agency (ESA) Calibration/Validation Strategy for Optical Land-Imaging Satellites and Pathway towards Interoperability. - Fabrizio Niro; Philippe Goryl; Steffen Dransfeld; Valentina Boccia; Ferran Gascon; Jennifer Adams; Britta Themann; Silvia Scifoni; Georgia Doxani (Remote. Sens., 2021)