@article{eprints650,
            note = {  PACS:  05.45.Tp Time series analysis

    05.40.Fb Random walks and Levy flights

    89.90.+n Other topics in areas of applied and interdisciplinary physics (restricted to new topics in section 89)
},
       publisher = {EDP Sciences},
         journal = {EPL (Europhysics Letters)},
          author = {Fabio Pammolli and Kaushik Matia and Dongfeng Fu and Sergey V. Buldyrev and Massimo Riccaboni and H. Eugene Stanley},
           title = {Statistical properties of business firms structure and growth},
            year = {2004},
          volume = {67},
           pages = {498},
          number = {3},
             url = {http://eprints.imtlucca.it/650/},
        abstract = {We analyze a database comprising quarterly sales of 55624 pharmaceutical products commercialized by 3939 pharmaceutical firms in the period 1992-2001. We study the probability density function (PDF) of growth in firms and product sales and find that the width of the PDF of growth decays with the sales as a power law with exponent {\^I}? = 0.20 {\^A}{$\pm$} 0.01. We also find that the average sales of products scales with the firm sales as a power law with exponent {\^I}{$\pm$} = 0.57 {\^A}{$\pm$} 0.02. And that the average number products of a firm scales with the firm sales as a power law with exponent {\^I}? = 0.42 {\^A}{$\pm$} 0.02. We compare these findings with the predictions of models proposed till date on growth of business firms.}
}