Add MARC 21 to "Related standards"

[JordanLyons]

The Library of Congress has a format called MARC 21 for community information that should maybe be included in the "Related standards" section. It was referenced in a library science article I read about information and referral.

[NeilMcKLogic]

Hey this is pretty interesting @JordanLyons . Have you looked closely to see to what degree it has a similar data structure and elements as HSDS?

[JordanLyons]

I found out about it in this academic paper that compares it to the AIRS format: https://www-emeraldinsight-com.weblib.lib.umt.edu:2443/doi/full/10.1108/JD-10-2014-0141