Vilas, Howard K., and John O. Surtees. “Analysis of Knee-Braced Portal Frames for Vertical Loading: Part 2-Columns of Unequal Stiffness”. Engineering Journal 21, no. 4 (December 31, 1984): 223–226. Accessed June 7, 2025. https://ej.aisc.org/index.php/engj/article/view/427.