H. Aher, P. Shirode, K. Shinde, und A. Jadhav. International Journal on Recent and Innovation Trends in Computing and Communication, 3 (1):
46--51(Januar 2015)
S. Baker. 8th International Conference of the European Society for Ecological Economics, Seite 1--17. Ljubljana, European Society for Ecological Economics, ESEE, (Juni 2009)