@article { Penserini2007,
	title = {High variability design for software agents: Extending Tropos},
	journal = {ACM Transactions on Autonomous and Adaptive Systems (TAAS)},
	volume = {2},
	number = {4},
	year = {2007},
	author = {Penserini, L. and Perini, A. and Susi, A. and Mylopoulos, J.}
}