\Bibitem{Pro88} \by D.~V.~Prokhorov \paper Level curves of functions convex in the direction of an axis \jour Mat. Zametki \yr 1988 \vol 44 \issue 4 \pages 523--527 \mathnet{http://mi.mathnet.ru/mzm4241} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=975192} \zmath{https://zbmath.org/?q=an:0651.30013|0667.30008} \transl \jour Math. Notes \yr 1988 \vol 44 \issue 4 \pages 767--769 \crossref{https://doi.org/10.1007/BF01158922} \isi{https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=Publons&SrcAuth=Publons_CEL&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=A1988U847500022}