Westall, Frances; et al. (2001). „Early Archean fossil bacteria and biofilms in hydrothermally influenced sediments from the Barberton greenstone belt, South Africa”. Precambrian Research. 106 (1–2): 93—116. Bibcode:2001PreR..106...93W. doi:10.1016/S0301-9268(00)00127-3.
Westall, Frances; et al. (2001). „Early Archean fossil bacteria and biofilms in hydrothermally influenced sediments from the Barberton greenstone belt, South Africa”. Precambrian Research. 106 (1–2): 93—116. Bibcode:2001PreR..106...93W. doi:10.1016/S0301-9268(00)00127-3.