The Collection Fusion Problem.

@inproceedings{voorhees-1994-collection, author = {Ellen M. Voorhees and Narendra Kumar Gupta and Ben Johnson-Laird}, editor = {Donna K. Harman}, title = {{The Collection Fusion Problem}}, booktitle = {{Proceedings of The Third Text REtrieval Conference, TREC 1994, Gaithersburg, Maryland, USA, November 2-4, 1994}}, series = {NIST Special Publication}, volume = {500-225}, pages = {95--104}, publisher = {National Institute of Standards and Technology (NIST)}, year = {1994}, url = {http://trec.nist.gov/pubs/trec3/papers/siemens_paper.ps.gz} }