David Ahn Sisay Fissaha Adafre Valentin Jijkoun Karin Müller Maarten de Rijke Erik F. Tjong Kim Sang Towards a Multi-Stream Question Answering-As-XML-Retrieval Strategy. 2005 TREC http://trec.nist.gov/pubs/trec14/papers/uamsterdam.qa.erik.pdf conf/trec/2005 db/conf/trec/trec2005.html#AhnAJMRS05