Kioussi, M.K. Angelis, Y.S. Cawley, A.T. Koupparis, M. Kazlauskas, R. Brenna, J.T. Georgakopoulos, C.G., External calibration in Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry measurements of endogenous androgenic anabolic steroids in sports doping control, Journal of Chromatography A, (1218), 5675-5682, 2011,