David J. Bell Ian Ruthven Searcher's Assessments of Task Complexity for Web Searching. 57-71 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2997&spage=57 2004 conf/ecir/2004 ECIR db/conf/ecir/ecir2004.html#BellR04