Photodentro OER repositories have been co-financed by the European Union (ESF) and the Greek State in the context of the “Digital Educational Platform, Interactive Books, and Learning Object Repository" program (#296441) of the Greek National Strategic Reference Framework (NSRF) 2007-2013 (Operational program Education and Lifelong Learning); they are currently being expanded and improved in the context of the “Digital School II: Expanding and Exploiting the Digital Educational Platform, the OER Repositories and the Interactive Textbooks” program (#5001312) of the NSRF 2014-2020 (Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020). Program Beneficiary (program coordinator & implementer): Computer Technology Institute and Press – “DIOPHANTUS” (CTI) (www.cti.gr).