angular distributions (Giller et al. 2005a) i.e. their independence of the primary particle energy or mass. It was shown that integrated over electron energies and lateral distances the angular distributions depended on the shower age only. Next they were studied for fixed electron energies (Giller et al. 2005b) and it turned out that in this case the angular distributions did not depend even on the shower age. It should actually be expected since the electron angle depends mainly on the electron actual energy, and very weakly on its energy in the past.\
A similar study was done later by Nerling et al.(2006) although their choice of rather large energy ranges was probably the reason for not quite confirming the independence of the angular distributions on shower age since the energy spectra within the ranges do depend on the age.\
The idea for analysing electron distributions for their fixed energies was developed later by Lafebre et al. (2009) who studied various electron distributions in showers. They confirmed the independence of the angular distributions for fixed energies of the shower age and claimed their universal character with respect to the changes of the primary particle, its mass, energy or the incidence angle 