\Bibitem{ZelBor90} \by M.~I.~Zelikin, V.~F.~Borisov \paper Synthesis in problems of optimal control containing trajectories with participating switchings and singular trajectories of the second order \jour Mat. Zametki \yr 1990 \vol 47 \issue 1 \pages 62--73 \mathnet{http://mi.mathnet.ru/mzm3139} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=1048262} \zmath{https://zbmath.org/?q=an:0709.49002|0698.49010} \transl \jour Math. Notes \yr 1990 \vol 47 \issue 1 \pages 41--49 \crossref{https://doi.org/10.1007/BF01157282} \isi{https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=Publons&SrcAuth=Publons_CEL&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=A1990EA94100006}