[1] [CITE@en[DCMI: Dublin Core™ Collection Description Frequency Vocabulary]], [TIME[2021-01-11T08:57:08.000Z]], [TIME[2021-01-13T09:37:26.916Z]] <https://www.dublincore.org/specifications/dublin-core/collection-description/frequency/>

[2] [CITE@en[DCMI: Dublin Core™ Collection Description Terms]], [TIME[2021-01-18T09:36:38.000Z]], [TIME[2021-01-18T11:25:31.009Z]] <https://www.dublincore.org/specifications/dublin-core/collection-description/collection-terms/#cldFrequency>

[3] [CITE@en[DCMI: Domains and Ranges for DCMI Properties]], [TIME[2021-01-18T09:36:38.000Z]], [TIME[2021-01-20T08:33:36.927Z]] <https://www.dublincore.org/specifications/dublin-core/domain-range/#Frequency>