Preface. Accretion Disk Theory: From the Standard Model until Advection; G.S. Bisnovatyi-Kogan. Accretion Disks around Black Holes: Twenty-Five Years Later; S.K. Chakrabarti. Viscosity in Accretion Disks; P.J. Wiita. Shock Formation in Adiabatic Accretion Flows around a Kerr...