Wang, F. Y., Bromm, V., Greif, T. H., Stacy, A., Dai, Z. G., Loeb, A., et al. (2012). Probing pre-galactic metal enrichment with high-redshift gamma-ray bursts. The Astrophysical Journal, 760(1): 27, pp. 1-13. doi:10.1088/0004-637X/760/1/27.