1. Studies on eigenvalues in beam vibration;Nakagawa,1968
2. A method of minimization of square sum of the natural periods of vibration of a frame;Nakagawa;Comput. Struct.,1989
3. A design method of structures to minimize the square sum of natural periods of vibration;Nakagawa;Comput. Struct.,1992
4. A proposal for analytic technique on optimum design method of frame structure;Takagai,1993
5. Specifications for Highway Bridges,1989