  Aiming to find new extremely metal-deficient star-forming galaxies we
extracted from the Two-Degree Field Galaxy Redshift Survey (2dFGRS) 100K Data
Release 14 emission-line galaxies with relatively strong [OIII] 4363 emission.
Spectroscopic and photometric studies of this sample and, in addition, of 7
Tololo and 2 UM galaxies were performed on the basis of observations with the
ESO 3.6m telescope. All sample galaxies qualify with respect to their
photometric and spectroscopic properties as blue compact dwarf (BCD) galaxies.
Additionally, they show a good overlap with a comparison sample of 100
well-studied emission-line galaxies on the 12+log(O/H) vs. log(Ne/O), log(Ar/O)
and log(Fe/O) planes. From the analysis of the 2dFGRS subsample we report the
discovery of two new extremely metal-deficient BCDs with an oxygen abundance
12+log(O/H) < 7.6 and of another seven galaxies with 12+log(O/H) < 7.8.
Furthermore, we confirm previous oxygen abundance determinations for the BCDs
Tol 1304-353, Tol 2146-391, UM 559 and UM 570 to be 12+log(O/H) < 7.8.
