Philippine Rice Research Institute. (2009). OPAPA: The Open Academy for Philippine Agriculture : an innovation in accessing modern agricultural technologies. Philippine Rice Research Institute.
Chicago-referens (17:e uppl.)Philippine Rice Research Institute. OPAPA: The Open Academy for Philippine Agriculture : An Innovation in Accessing Modern Agricultural Technologies. Nueva Ecija: Philippine Rice Research Institute, 2009.
MLA-referens (9:e uppl.)Philippine Rice Research Institute. OPAPA: The Open Academy for Philippine Agriculture : An Innovation in Accessing Modern Agricultural Technologies. Philippine Rice Research Institute, 2009.
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