  We investigate three different approaches for fitting the degree
distributions of China-, US- and the composite China+US air network, in order
to reveal the nature of such distributions and the potential theoretical
background on which they are based. Our first approach is the fitting with
q-statistics probability distribution, done separately in two regimes. This
yields acceptable outcomes but generates two sets of fitting parameters. The
second approach is an entire fitting to all data points with the formula
proposed by Tsallis et al. So far, this trial is not able to produce consistent
results. In the third approach, we fit the data with two composite
distributions which may lack theoretical support for the moment.
