Gillies, A. G., and R. Shepherd. “Prediction of Post-Elastic Seismic Response of Structures by a Mode Superpostion technique
”. Bulletin of the New Zealand Society for Earthquake Engineering 16, no. 3 (September 30, 1983): 222–233. Accessed October 12, 2025. https://www.bulletin.nzsee.org.nz/index.php/bnzsee/article/view/922.