Darling, Janina K.; Architecture of Greece, 2004, Greenwood Publishing Group, ISBN 0313321523, 9780313321528, google books - good account of the Athens Propylaea on pp. 142–145, available online Dinsmoor, William Bell (1922), "Structural Iron in Greek Architecture," American Journal of Archaeology, XXVI Dinsmoor, W. B., The Architecture of Ancient Greece (New York, 1975 - but actually a reprint of the 1950 publication).