@inbook {series/sci/NikolopoulosCGPKV11,
	title = {Leveraging Massive User Contributions for Knowledge Extraction},
	booktitle = {Next Generation Data Technologies for Collective Computational Intelligence},
	series = {Studies in Computational Intelligence},
	volume = {352},
	year = {2011},
	pages = {415-443},
	publisher = {Springer},
	organization = {Springer},
	isbn = {978-3-642-20343-5},
	author = {Nikolopoulos, Spiros and Chatzilari, Elisavet and Giannakidou, Eirini and Symeon Papadopoulos and Yiannis Kompatsiaris and Athena Vakali},
	editor = {Bessis, Nik and Xhafa, Fatos}
}