Hiroshi Nakagawa Tatsunori Mori Noriko Kando Preface to the special issues on NTCIR-4. 237-242 2005 4 ACM Trans. Asian Lang. Inf. Process. 3 http://doi.acm.org/10.1145/1111667.1111668 db/journals/talip/talip4.html#NakagawaMK05