NII Testbeds and Community for Information Access Research 14th International Conference, NTCIR 2019, Tokyo, Japan, June 10-13, 2019, Revised Selected Papers - Kato, Makoto P.; Kato, Makoto P.; Liu, Yiqun; Liu, Yiqun; Kando, Noriko; Kando, Noriko; Clarke, Charles L. A.; Clarke, Charles L. A. (Springer International Publishing : Imprint: Springer, 2019)