NHK Kotoba No Kyoiku Sodan by Kiyomatsu Okuma (4140110341 9784140110348 4-14-011034-1)
Nyu Media Yogo Jiten by Kyoichi Takeshita, Nihon Hoso Shuppan Kyokai (4140110384 9784140110386 4-14-011038-4)
