F. Abel, M. Frank, N. Henze, D. Krause, and P. Siehndel. 2nd International Conference on Weblogs and Social Media (ICWSM 2008), Seattle, USA., page 230--231. Menlo Park, California, The AAAI Press, (April 2008)
F. Abel, E. Diaz-Aviles, N. Henze, D. Krause, and P. Siehndel. International Conference on Advances in Social Networks
Analysis and Mining, ASONAM 2010, Odense, Denmark, August
9-11, 2010, page 276-280. IEEE Computer Society, (2010)