Kim, S. I., Lee, J. H., Lee, P. G. and Kim, C. E. (2010) “Comparison of measured natural
                           frequencies of a railway bridge specimen between different excitation methods.” Journal
                           of The Korean Society of Civil Engineers, Vol. 30, No. 6A, pp. 535-542 (in Korean).Kim,
                           S. I., Lee, J. H., Lee, P. G. and Kim, C. E. (2010) “Comparison of measured natural
                           frequencies of a railway bridge specimen between different excitation methods.” Journal
                           of The Korean Society of Civil Engineers, Vol. 30, No. 6A, pp. 535-542 (in Korean).
