Torlakovic EE, Francis G, Garratt J, Gilks B, Hyjek E, Ibrahim M, Miller R, Nielsen S, Petcu EB, Swanson PE, Taylor CR, Vyberg M. Standardization of negative controls in diagnostic immunohistochemistry: recommendations from the international ad hoc expert panel. Appl Immunohistochem Mol Morphol. 2014 Apr; 22(4):241-52.