\Bibitem{Gue29} \by J.~Gueronimus \paper Sur un probl\`eme de Tchebyscheff \jour Sb. Math. \yr 1929 \vol 36 \issue 2 \mathnet{http://mi.mathnet.ru/eng/sm7346} \zmath{https://zbmath.org/?q=an:55.0798.01}