E. Guy. Proceedings of ATIT 2004, The First International Workshop on Activity Theory Based Practical Methods for IT Design, page 33-48. Copenhagen, Denmark, University of Aarhus, (2004)
L. Mcdowell, O. Etzioni, A. Halevy, and H. Levy. WWW '04: Proceedings of the 13th international conference on World Wide Web, page 244--254. New York, NY, USA, ACM Press, (2004)
X. Dong, A. Halevy, and J. Madhavan. SIGMOD '05: Proceedings of the 2005 ACM SIGMOD international conference on Management of data, page 85--96. New York, NY, USA, ACM Press, (2005)