1. On the state of stress in a plastic-rigid body at the yield point;Hill, R.;Philos. Mag. (7),1951
2. D. C. Drucker, H. J. Greenberg and W. Prager, The safety factor of an elastic-plastic body in plane strain, ASME, paper No. 51-A3
3. Extended limit design theorems for continuous media;Drucker, D. C.;Quart. Appl. Math.,1952
4. D. C. Drucker, Limit analysis of cylindrical shells under axially-symmetric loading, Proc. 1st Midwest. Conf. Solids Mech., Urbana, Ill. 1953, pp. 158-163
5. Limit analysis of arches;Onat, E. T.;J. Mech. Phys. Solids,1953