Library of Congress. Network Development and MARC Standards Office. MARC code list for languages [online]. 2007 edition, [Updated continuously to incorporate additions and changes (HTML only)]. Washington (D.C.): The Library of Congress, 2011-09-08 [cit. 2014-03-17]. Dostupné z: http://www.loc.gov/marc/languages/ a z: http://www.loc.gov/standards/codelists/languages.xml.
Dostupné standardně ve formátu HTML z: http://www.loc.gov/marc/languages/. Verze ve formátu XML dostupná z: http://www.loc.gov/standards/codelists/languages.xml.