https://www.ssc.wisc.edu/~hemken/MPlus/Basics/Grouped/Grouped_Analysis.html#grouped-confirmatory-factor-analysis
http://joophox.net/publist/CecklistMeasInv.pdf
http://www.statmodel.com/download/Topic%201.pdf
http://www.statmodel.com/discussion/messages/9/703.html?1527896840
Steenkamp, J. B. E., & Baumgartner, H. (1998). Assessing measurement invariance in cross-national consumer research. Journal of consumer research, 25(1), 78-90.
PERFECT MPLUS SYNTAX EXPLAINED FOR Measurement Invariance:
http://comm.eval.org/HigherLogic/System/DownloadDocumentFile.ashx?DocumentFileKey=63758fed-a490-43f2-8862-2de0217a08b8
