2021-04-20t17：28：11z http://oaipmh.hindawi.com/oai-pmh/oai.aspx. oai_dc. http://www.openarchives.org/oai/2.0/oai_dc.xsd. http://www.openarchives.org/oai/2.0/oai_dc/ oai_dc_agris. http://www.fao.org/agris/agmes/dtd/dlio.dtd. http://www.fao.org/agris/agmes/dtd/ Marc21. http://www.loc.gov/standards/marcxml/schema/marc21slim.xsd. http://www.loc.gov/marc21/slim.