Analysis of labor productivity using large-scale data of firm's financial statements Y. Ikeda, W. Souma, H. Aoyama, Y. Fujiwara and H. Iyetomi Eur. Phys. J. B, 76 4 (2010) 491-499 Published online: 08 December 2009 DOI: 10.1140/epjb/e2009-00421-y