V. verbickij, editor (1884), “тӧк-”, in Slovarʹ Altajskago i Aladagskago narečij tjurkskago jazyka [Altaian and Aladagian language Dictionary], Kazan', →ISBN
“тӧк-”, in Grammatika Altajskovo Jazyka [Altaic language Grammar], Kazan: V universtiteskoj til, 1869, →ISBN, page 92