Literature：Yagi Kazuo Sakuhin-shū (The Work of Yagi Kazuo) Wareme no aru futatsu no ana (Crevice with Two Holes), 1967, Photographed by Narahara Ikkō, Edited by Unagami Masaomi, Published by Ishihara Ryūichi and Kyūryūdō, Tokyo in 1969, Edition of 800 copies.

Gendai-no-Tōgei (Modern Ceramics) Vol.12, Yagi Kazuo, Suzuki Osamu and Kamoda Shōji, Wareme no aru futatsu no ana (Crevice with Two Holes), 1967 (p32/Plate No 18-19) Edited by Inui Yoshiaki, Published by Kōdansha, Tokyo, 1975

Yakimono Kono Gendai (Ceramic Art, This present age) Chiisana waremeno aru ana (Hole with a Small Crevice), 1967, Written by Unagami Masaomi, published by Bunka Shuppankyoku, printed by Ōnuma Jun, 1988 (P4)

*In the two publications published in 1969 and 1975 referred above, the piece was titled both as Wareme no aru futatsu no ana (Crevice with Two Holes) but is the same piece as now known as Chiisana waremeno aru ana (Hole with a Small Crevice). Yagi often changed the title of his work.