ISO 639-1: Codes for the representation of names of languages -- Part 1: Alpha-2 code
The code set is available from http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm? csnumber=22109&ICS1=1&ICS2=140&ICS3=20
iso639-1_iso639-1
http://purl.bioontology.org/ontology/HL7/iso639-1_iso639-1