Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An extended universality of electron distributions in cosmic ray showers
  of high energies and its application   It is shown that the shape of any electron distribution in a high energy air
shower is the same in all such showers, if taken at the same age, independently
of the primary energy, mass and thus, of the interaction model.

23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph