Irvine, H. M. “Slenderness Effects in Earthquake Resisting Frames” - A. L. Andrews: Bulletin of N.Z. National Society for Earthquake Engineering, Vol. 10, No. 3 , September, 1977. BNZSEE 1978, 11 (1), 71-75. https://doi.org/10.5459/bnzsee.11.1.71-75.