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We present a sample of low-redshift (z<0.133) candidates for extremelylow-metallicity star-forming galaxies with oxygen abundances 12+logO/H<7.4selected from the Data Release 14 (DR14) of the Sloan Digital Sky Survey(SDSS). Three methods are used to derive their oxygen abundances. Among thesemethods two are based on strong [OII]3727, [OIII]4959, and [OIII]5007 emissionlines, which we call strong-line and semi-empirical methods. These were appliedfor all galaxies. We have developed one of these methods, the strong-linemethod, in this paper. This method is specifically focused on the accuratedetermination of metallicity in extremely low-metallicity galaxies and may notbe used at higher metallicities with12+logO/H>7.5. The third, the direct Temethod, was applied for galaxies with detected [OIII]4363 emission lines. Allthree methods give consistent abundances and can be used in combination orseparately for selection of lowest-metallicity candidates. However, thestrong-line method is preferable for spectra with a poorly detected orundetected [OIII]4363 emission line. In total, our list of selected candidatesfor extremely low-metallicity galaxies includes 66 objects.

Low-redshift lowest-metallicity star-forming galaxies in the SDSS DR14