R. Krestel, G. Demartini, and E. Herder. Proc. of 2011 Joint International Conference on Digital Libraries (JCDL 2011), Ottawa, Ontario, Canada, June 13-17, 2011. ACM., (2011)
A. Stewart, E. Herder, M. Smith, and W. Nejdl. Digital Ecosystems and Technologies Conference (DEST), 2011 Proceedings of the 5th IEEE International Conference on, page 127 -132. (31 2011-june 3 2011)