L. Billard, M. Shim, and G. Pesti, “Experimental Design and Analysis with Emphasis on Communicating What Has Been Done: (II) Calculating Interaction Contrasts with SAS”, Int. J. Poult. Sci., vol. 13, no. 2, pp. 88–96, Jan. 2014, doi: 10.3923/ijps.2014.88.96.