\Bibitem{Pot62} \by D.~B.~Potyagailo \paper On~a~class of Riemann surface \jour Sb. Math. \yr 1962 \vol 98 \issue 4 \mathnet{http://mi.mathnet.ru//eng/sm4631} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=147641} \zmath{https://zbmath.org/?q=an:0107.06601}