Steven Schockaert David Ahn Martine De Cock Etienne E. Kerre Question Answering with Imperfect Temporal Information. 647-658 2006 conf/fqas/2006 FQAS http://dx.doi.org/10.1007/11766254_55 db/conf/fqas/fqas2006.html#SchockaertACK06