1. Berkowski P., Approximate second order analysis of unbraced multistory steel frames, Proc. of the International Conference on “Metal Structures”, Gdansk, Poland, 1989.
2. Berkowski P., Boron J., Synthesis of Some Structures with the “BackTrack Discrete Programming Method”, (in polish),Inz. i Bud., 43/86, s.204–208.
3. Berkowski P., Discrete Optimization of Highrise Steel Frames, International Conference on Highrise Buildings, Nanjing’89, China.
4. Birnstiel C., Iffland J.S., Factors Influencing Frame Stabili-ty, J. Struct. Div., Proc.ASCE, 106, ST2, Feb. 1980, 491–504,
5. Fellippa, C.A., Error Analysis Of Penalty Function Techniques For Constraint Definition In Linear Algebraic Systems, Inter.J.Num.Meth.Eng.,Vol 11, 1977, 709–728.