Ohtomo Y, Kakegawa T, Ishida A, Nagase T, Rosing MT. "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7 (1). 8 December 2013: 25–28. Bibcode:2014NatGe...7...25O. doi:10.1038/ngeo2025.
Ohtomo Y, Kakegawa T, Ishida A, Nagase T, Rosing MT. "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7 (1). 8 December 2013: 25–28. Bibcode:2014NatGe...7...25O. doi:10.1038/ngeo2025.