Maruyama, Sumio; Tao, Xu-Tang; Hokari, Hirofumi; Noh, Taeyong; Zhang, Yadong; Wada, Tatsuo; Sasabe, Hiroyuki; Suzuki, Hironori; Watanabe, Toshiyuki; Miyata, Seizo Journal of Materials Chemistry, 1999 , vol. 9, # 4 p. 893 - 898