\Bibitem{Ngu93} \by Nguyen~Thien~Nam \paper Spectrum of nonlinear integral equations and the widths of function classes \jour Mat. Zametki \yr 1993 \vol 53 \issue 4 \pages 101--110 \mathnet{http://mi.mathnet.ru/mzm2327} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=1240866} \zmath{https://zbmath.org/?q=an:0801.45004} \elib{https://elibrary.ru/item.asp?id=12736084} \transl \jour Math. Notes \yr 1993 \vol 53 \issue 4 \pages 424--429 \crossref{https://doi.org/10.1007/BF01210226} \isi{https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=Publons&SrcAuth=Publons_CEL&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=A1993MY10700031}