E. Zangerle, C. Bauer, and A. Said. Proceedings of the Fifteenth ACM Conference on Recommender Systems, page 794-795. New York, NY, USA, ACM, (September 2021)
M. Zanin, P. Cano, J. Buldú, and O. Celma. CEA'08: Proceedings of the 2nd WSEAS International Conference on Computer Engineering and Applications, page 120--124. Stevens Point, Wisconsin, USA, World Scientific and Engineering Academy and Society (WSEAS), (2008)