Colloquium on Variable Stars : International Astronomical Union combined colloquium of the Commissions 27 and 42, Bamberg, 1965, August 11-14, with the theme, The position of variable stars in the Hertzsprung-Russell diagram (Veroffentlichungen der Remeis-Sternwarte Bamberg, Astronomisches Institut der Universitat Erlangen-Nurnberg ;, 1965)