\Bibitem{ButKar95} \by V.~F.~Butuzov, A.~F.~Karashchuk \paper One singularly perturbed system of partial differential equations of the first order \jour Mat. Zametki \yr 1995 \vol 57 \issue 3 \pages 338--349 \mathnet{http://mi.mathnet.ru/mzm1956} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=1346433} \zmath{https://zbmath.org/?q=an:0859.35007} \transl \jour Math. Notes \yr 1995 \vol 57 \issue 3 \pages 240--247 \crossref{https://doi.org/10.1007/BF02303968} \isi{https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=Publons&SrcAuth=Publons_CEL&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=A1995TJ91400003}