Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for and study of extremely metal-deficient galaxies   We summarize the progress in identifying and observational study of extremely
metal-deficient (XMD) gas-rich galaxies (BCGs, dIr and LSBDs). Due to volume
limitations only following issues are addressed: sample creation, some
statistical data, Colour-Magnitude Diagrams (CMD) and ages, the case of SBS
0335--052 system, and probable evolution paths of various XMD objects.

20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
2
The categories of this paper are: math