^Tsumura, K. (1966): "He died a Samurai's death: Two world Judo leaders defend the honour of G. K. Koizumi, Founder of British Judo, who took his own life." Black Belt, 4(6):48–50.
^Itoh, K. (2001): The Japanese community in pre-war Britain: From integration to disintegration (pp. 27–28). Surrey, UK: Curzon. (ISBN0-7007-1487-1)