How to add Russian interface language to AT&T Galaxy Note 3 N900A ?

My father in law just bought an AT&T Galaxy Note 3 SM-N900A from Amazon and he can't change the device language to Russian because it doesn't have Russian in the languages.
Is there a way to add Russian to the device language ?
Or is it possible to flash the Russian version of the SM-N900 rom from SamMobile that is not related to AT&T ?