ieice1994hirashima
PDF file: Tsukasa Hirashima, Toshitada Niitsu, Kentaro Hirose, Akihiro Kashihara and Jun'ichi Toyoda, "An Indexing Framework for Adaptive Arrangement of Mechanics Problems for ITS", IEICE Trans. Inf.& Syst., Vol.E77-D, No.1, pp.19-26(1994).