Automorphism Groups of Compact Planar Klein Surfaces. Emilio Bujalance (1986) Manuscripta mathematica
Automorphisms of Riemann surfaces with two fixed points Tomasz Szemberg (1991) Annales Polonici Mathematici We give an upper bound for the order of an automorphism of a Riemann surface with two fixed points. The main results are presented in Theorems 1.4 and 2.4.