1. Adams, M. J. (1998). The principles of multivariate data analysis. In P. R. Ashurst & M. J. Dennis (Eds.), Analytical methods of food authentication (p. 350). London: Blackie Academic & Professional.
2. Aiken, R. S., Leigh, C. H., Leinbach, T. R., & Moss, M. R. (1982). Development and environment in Peninsular Malaysia. Singapore: McGraw-Hill International Book Company.
3. Alberto, W. D., Pilar, D. M. D., Valeria, A. M., Fabiana, P. S., Cecilia, H. A., et al. (2001). Pattern recognition techniques for the evaluation of spatial and temporal variations in water quality. A case study: Squia River Basin (Cordoba-Argentina). Water Research, 35, 2881–2894. doi: 10.1016/S0043-1354(00)00592-3 .
4. Arheimer, P. V., & Swank, W. T. (2000). Nitrogen and phosphorus concentrations from agriculture catchments—Influence of spatial and temporal variables. Journal of Hydrology (Amsterdam), 227(1–4), 140–159. doi: 10.1016/S0022-1694(99)00177-8 .
5. Barnes, I., Kistler, R. W., Mariner, R. H., & Presser, T. H. (1981). Geochemical evidence on the nature of the basement rocks of the Sierra Nevada, California. U.S. Geological Survey Water Supply Paper, 2181.