\Bibitem{BroGokKre70} \by V.~M.~Brodskii, I.~Ts.~Gokhberg, M.~G.~Krein \paper Determination and fundamental properties of the characteristic function of $\mathcal{Y}$-node \jour Funktsional. Anal. i Prilozhen. \yr 1970 \vol 4 \issue 1 \pages 88--90 \mathnet{http://mi.mathnet.ru/faa2640} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=487517} \zmath{https://zbmath.org/?q=an:0203.13803} \transl \jour Funct. Anal. Appl. \yr 1970 \vol 4 \issue 1 \pages 78--80 \crossref{https://doi.org/10.1007/BF01075624}