CCSDS Secretariat, Space Communications and Navigation Office, 7L70, Space Operations Mission Directorate. Reference Model for an Open Archival Information System (OAIS), book, August 2009; (https://digital.library.unt.edu/ark:/67531/metadc123534/m1/1/: accessed April 24, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .