Johnson, J. L., Muller, K. E., Slaughter, J. C., Gurka, M. . J. ., Gribbin, M. . J. ., & Simpson, S. L. (2009). POWERLIB: SAS/IML Software for Computing Power in Multivariate Linear Models. Journal of Statistical Software, 30(5), 1–27. https://doi.org/10.18637/jss.v030.i05