1. Agarwal, V. B., & Yochum, G. R. (1999). Tourist spending and race of visitors. Journal of Travel Research, 38(2), 173–176.
2. Agrell, P. J. (1995). Interactive multi-criteria decision making in production economics. Linkoeping: Production Economic Research.
3. Berkemer, R., Makowski, M., & Watkins, D. (1993). A prototype of a decision support system for river basin water quality management in Central and Eastern Europe. Laxenburg: WP-93-049.
4. Breidert, C., Hahsler, M., & Reutterer, T. (2006). A review of methods for measuring willingness-to-pay. Innovative Marketing, 2(4), 8–32.
5. Brown, S. (2002). Measuring carbon in forests: current status and future challenges. Environmental Pollution, 116(3), 363–372.