\Bibitem{Bak70} \by I.~A.~Bakhtin \paper Existence of common fixed points for commutative sets of nonlinear operators \jour Funktsional. Anal. i Prilozhen. \yr 1970 \vol 4 \issue 1 \pages 86--87 \mathnet{http://mi.mathnet.ru/faa2639} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=267431} \zmath{https://zbmath.org/?q=an:0198.47904} \transl \jour Funct. Anal. Appl. \yr 1970 \vol 4 \issue 1 \pages 76--77 \crossref{https://doi.org/10.1007/BF01075623}