ESDU Struct 02.01.46 gives a graph from which the buckling coefficient of the plate may be obtained. Four curves are plotted against the ratio of the plate length to its width (measured normal to the unswept edges) for values of the sweep of the edge of 0 (a rectangular plate), 30, 40 and 45 degrees. The buckling stress coefficient is defined as the stress at buckling non-dimensionalised by the modulus of elasticity of the material and factored by the square of the ratio of the plate width to its thickness. The curves relate to an isotropic material having a Poisson's ratio of 0.3.