Z. Liu, A. Bateman, S. Sohail, B. Zinner, and D. Roland Sr., “Statistical Sensitivity Required to Detect Any Potential Difference of Bioavailability Between DL-Methionine and DL-Methionine Hydroxy Analogue in Layers”, Int. J. Poult. Sci., vol. 3, no. 11, pp. 697–703, Oct. 2004, doi: 10.3923/ijps.2004.697.703.