Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Measurement of the Proton Structure Function $F_2$ and the Extraction of
  the Gluon Density at Small $x$
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an