'rus' is an ISO 639-3 code.
ISO 639-3 link
URL
http://www-01.sil.org/iso639-3/documentation.asp?id=rus
http://glottolog.org/resource/languoid/iso/rus
http://www.hortensj-garden.org/index.php?tnc=1&tr=i639&nid=ISO-639-3-Language-rus
http://phoible.org/languages/rus
http://www.language-archives.org/language/rus
http://multitree.org/codes/rus
http://odin.linguistlist.org/igt_urls.php?lang=rus
http://tsammalex.clld.org/languages/rus
http://www.lexvo.org/id/iso639-3/rus
https://tools.wmflabs.org/wikidata-todo/resolver.php?prop=220&value=rus
https://tools.wmflabs.org/wikidata-todo/resolver.php?prop=220&project=enwiki&value=rus
http://archive.ethnologue.com/16/show_language.asp?code=rus
http://www.languagesandnumbers.com/how-to-count-in-romani/en/rus
https://en.wikipedia.org/wiki/ISO_639:rus
http://dbpedia.org/page/ISO_639:rus
no ISO 639-3 link
StatusISO 639-3URL
NO ISO, WOLDenghttp://wold.clld.org/language/13
NO ISO, WALSdeuhttp://wals.info/languoid/lect/wals_code_ger
NO ISO, ASJPenghttp://asjp.clld.org/languages/ENGLISH
NO ISO, AfBodeuhttp://afbo.info/languages/115