Hannan, C. J., Friedl, K. E., Zold, A., Kettler, T. M., & al., et. (1991). Psychological and serum homovanillic acid changes in men administered androgenic steroids. Psychoneuroendocrinology, 16(4), 335–343. Elsevier Science, Ltd/Pergamon, US,  http://www.elsevier.nl