Choi, Y. J. ., J. . Lampel, D. . Jordan, S. . Fiedler, and T. Wagner. “Principal Component Analysis (PCA) of Buried Archaeological Remains by VIS-NIR Spectroscopy”. Archaeologia Polona, vol. 53, Jan. 2015, pp. 412-5, https://journals.iaepan.pl/apolona/article/view/363.