There references used in this bookdown are:

Courtiol, Alexandre, François Rousset, Marie-Sophie Rohwäder, David X. Soto, Linn Lehnert, Christian C. Voigt, Keith A. Hobson, Leonard I. Wassenaar, and Stephanie Kramer-Schadt. 2019. “Isoscape Computation and Inference of Spatial Origins with Mixed Models Using the r Package IsoriX.” In Tracking Animal Migration with Stable Isotopes, edited by Keith A. Hobson and Leonard I. Wassenaar, second. London: Academic Press.
Fisher, Ronald Aylmer. 1925. Statistical Methods for Research Workers. Genesis Publishing Pvt Ltd.