K. J. A. . Kairemo, A. J. . Kiuru, and J. J. . Heikkonen, “Image Subtraction Analysis with Technetium-99M Labeled Monoclonal Antibody and Colloid for Evaluation of Liver Lesions: Phantom Measurements and Patient Studies”, AO, vol. 32, no. 7-8, pp. 763–769, Jan. 1993.