The Critical Temperature of an Anisotropic Superconductor in the   Presence of a Homogeneous Magnetic Field and Impurities
  The effect of a homogeneous magnetic field and nonmagnetic impurities on the critical temperature of an anisotropic superconductor has been investigated. The role of these pair-breakers in relation to the anisotropy of the order parameter is clarified. 
G. Haran, J. Taylor and A. D. S. Nagi (University of Waterloo)