Canonical URIs for regional variants in multilingual dataset

Hi all,

I am looking for canonical URIs to represent regional variants in a multilingual dataset. 
Fo example, I want to be able to use all the variants of Spanish say es-XX(e.g., es-MX for Mexican variant for Spanish), or English (e.g., en-CA).
I was looking around, specially in the Library of Congress endpoint [1], but I am not able to have such URIs for geographical/regional variants. 

Any thoughts or pointers very much appreciated!

TIA.

Best,

Ghislain 

[1] http://id.loc.gov/download/ <http://id.loc.gov/download/> 

---------------------------------------
Ghislain A. Atemezing, Ph.D
Mail: ghislain.atemezing@gmail.com
Web: https://w3id.org/people/gatemezing <http://www.atemezing.org/>
Twitter: @gatemezing
About Me: https://about.me/ghislain.atemezing <https://about.me/ghislain.atemezing>