Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comments on the paper: Optical reflectance, optical refractive index and
  optical conductivity measurements of nonlinear optics for L-aspartic acid
  nickel chloride single crystal   We argue that the L-aspartic acid nickel chloride crystal reported by the
authors of the title paper (Optics Communications 2013) is actually the
well-known diaqua(L-aspartato)nickel(II) hydrate crystal.

0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph