1. Manual of steel construction . (1980). American Institute of Steel Construction 8th edition Chicago Ill.
2. Gomory R. E. (1960). “An algorithm for the mixed integer problem.” Report No. P‐1885 The Rand Corp. Santa Monica Calif.
3. Gorman M. R. (1984). “Optimum structural design by implicit enumeration.” Proc. 3rd Conf. on Computing in Civ. Engrg. ASCE San Diego Calif. April 675–681.