Remarks on the Nyquist and Callen-Welton Theorems
  The connection of the Callen-Welton and Nyquist fluctuation-dissipation relations is considered for plasma-like classical and quantum systems. The conditions for appearance of the dissipative parameters in the equilibrium current-current correlation function are investigated. The paper presents the arguments for the restrictions of the Nyquist theorem and against violation of the Callen-Welton theorem in the quantum case. 
S.A. Trigger, G.J.F. van Heijst, A.A. Rukhadze, P.P.J.M. Schram