\Bibitem{And71} \by K.~K.~Andreev \paper Letter to the editors \jour Algebra Logika \yr 1971 \vol 10 \issue 2 \pages 226--228 \mathnet{http://mi.mathnet.ru/al1295} \mathscinet{https://mathscinet.ams.org/mathscinet-getitem?mr=0296119}