DiTrapani J, Rockwood N, Jeon M. Explanatory IRT analysis using the SPIRT macro in SPSS. TQMP. 2018;14(2):81-98. doi: 10.20982/tqmp.14.2.p081
Beach RH, Poulos C, Pattanayak SK. Farm economics of bird flu. Revue Canadienne D'agroeconomie. 2007 Dec 1;55(4):471-83.