Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The CMBR Spectrum   A short review of the measured spectrum of the Cosmic Microwave Background
Radiation (CMBR) and implications. Extensions of the Kompaneets equation and
Sunyaev-Zel'dovich effect are given.

18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio