We may at least suspect that the Slavic vowel is not historically unconnected with its Ural-Altaic parallels.
"Language" by Edward Sapir
FINNO-TATARIC (Turanian, Ural-Altaic, &c.).
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 8" by Various
The Finno-Ugrian languages are distinguished from the other divisions of the Ural-Altaic group both in grammar and vocabulary.
"Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 4" by Various
Kan Pudai, Altaic story of, i.
"Zoological Mythology (Volume II)" by Angelo de Gubernatis