Jack Troy, Salt Glazed Ceramics, London: Pitman 1977. Signed and dated by Len Castle 1978; Edmund de Waal Ceramics, Design Source Book. London: New Holland 1999. Signed Len Castle; Henry Varnum Poor A Book of Pottery. From Mud Into Immortality. London: Pitman 1959. Signed and dated by Len Castle 1961; J.C. Schofield Materials for the New Zealand Potter. New Zealand Geological Survey 1977.