Bounded cohomology of subgroups of mapping class groups. Bestvina, Mladen; Fujiwara, Koji — 2002 Geometry & Topology
Parabolic isometries of CAT(0) spaces and CAT(0) dimensions. Fujiwara, Koji; Shioya, Takashi; Yamagata, Saeko — 2004 Algebraic & Geometric Topology