Entropy of nonlinear black holes in quadratic gravity
  Employing the Noether charge technique and Visser's Euclidean approach the entropy of the nonlinear black hole described by the perturbative solution of the system of coupled equations of the quadratic gravity and nonlinear electrodynamics is constructed. The solution is parametrized by the exact location of the event horizon and charge. Special emphasis in put on the extremal configuration. Consequences of the second choice of the boundary conditions, in which the solution is paramerized by the charge and the total mass as seen by a distant observer is briefly examined. 
Jerzy Matyjasek