\Bibitem{Dit85} \by A.~V.~Ditchev \paper D. Skordev's conjecture \jour Algebra Logika \yr 1985 \vol 24 \issue 4 \pages 379--391 \mathnet{http://mi.mathnet.ru/al1911} \mathscinet{https://mathscinet.ams.org/mathscinet-getitem?mr=830007}