Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topics in Basic Maser Theory   This review covers some of the developments in basic theory of astronomical
masers over the past ten years. Topics included are the effects of three
dimensional geometry and polarization, with special emphasis on the differences
between maser and non-maser radiation.

32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an