\Bibitem{Gut70} \by E.~A.~Gutkin \paper Representations of the principal series of a complex semisimple Lie group \jour Funktsional. Anal. i Prilozhen. \yr 1970 \vol 4 \issue 2 \pages 32--37 \mathnet{http://mi.mathnet.ru/faa2649} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=297924} \zmath{https://zbmath.org/?q=an:0225.22023} \transl \jour Funct. Anal. Appl. \yr 1970 \vol 4 \issue 2 \pages 117--121 \crossref{https://doi.org/10.1007/BF01094487}