\Bibitem{Res68} \by Yu.~G.~Reshetnyak \paper A condition for boundedness of the index for mappings with bounded distortion \jour Sibirsk. Mat. Zh. \yr 1968 \vol 9 \issue 2 \pages 368--374 \mathnet{http://mi.mathnet.ru/smj5520} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=0226005} \zmath{https://zbmath.org/?q=an:0162.38201} \transl \jour Siberian Math. J. \yr 1968 \vol 9 \issue 2 \pages 281--285 \crossref{https://doi.org/10.1007/BF02204791}