B. Madsen, H. (1980). John Ormsbee Simonds: Earthscape. A manual of environmental planning McGraw-Hill Book Company, New York 1978. XII, 340 s., ill. 31 cm. DM 71,50. Geografisk Tidsskrift, 80. Hentet fra https://tidsskrift.dk/geografisktidsskrift/article/view/45288