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Budaghyan, L.; Grigoryan, D.; Torosyan, L. A NECESSARY AND SUFFICIENT CONDITION FOR THE UNIQUENESS OF $ \beta\delta $-NORMAL FORM OF TYPED $ \lambda $-TERMS FOR THE CANONICAL NOTION OF $ \delta $-REDUCTION. Proc. YSU A: Phys. Math. Sci. 2019, 53, 28-36.