\Bibitem{Wey76} \by H.~Weyl \paper Mean motion \jour Russian Math. Surveys \yr 1976 \vol 31 \issue 4 \mathnet{http://mi.mathnet.ru/eng/rm3804} \mathscinet{https://mathscinet.ams.org/mathscinet-getitem?mr=414305} \zmath{https://zbmath.org/?q=an:0363.70012}