Chivian, D., E.L. Brodie, E.J. Alm, D.E. Culley, P.S. Dehal, T.Z. DeSantis, T.M. Gihring, et al. 2008. “Environmental Genomics Reveals a Single-Species Ecosystem Deep Within Earth”. Science 322: 275-78. doi:10.1126/science.1155495. Reference Link
Wanger, G., G. Southam, and T.C. Onstott. 2006. “Structural and Chemical Characterization of a Natural Fracture Surface from 2.8 Kilometers below Land Surface: Biofilms in the Deep Subsurface”. Handbook of Environmental Chemistry, Volume 5: Water Pollution 23: 443-52. doi:10.1080/01490450600875746. Reference Link