Are citations of scientific papers a case of nonextensivity?

The distribution N(x) of citations of scientific papers has recently been i llustrated (on ISI and PRE data sets) and analyzed by Redner (Eur. Phys. J. B 4, 131 (1998)). To fit the data, a stretched exponential (N(x) proportio nal to exp -(x/x(0))(beta)) has been used with only partial success. The su ccess is not complete because the data exhibit, for large citation count x, a power law (roughly N(x) proportional to x(-3) for the ISI data), which, clearly, the stretched exponential does not reproduce. This fact is then at tributed to a possibly different nature of rarely cited and largely cited p apers. We show here that, within a nonextensive thermostatistical formalism , the same data can be quite satisfactorily fitted with a single curve (nam ely, N(x) proportional to 1/[1 + (q - 1) lambda x](q/q-1) for the available values of x. This is consistent with the connection recently established b y Denisov (Phys. Lett. A 235, 447 (1997)) between this nonextensive formali sm and the Zipf-Mandelbrot law. What the present analysis ultimately sugges ts is that, in contrast to Redner's conclusion, the phenomenon might essent ially be one and the sane along the entire range of the citation number x.