Sheik, C. S., Reese, B. K., Twing, K. I., Sylvan, J. B., Grim, S. L., Schrenk, M. O., … Colwell, F. S. (2018). Identification and Removal of Contaminant Sequences From Ribosomal Gene Databases: Lessons From the Census of Deep Life. Frontiers in Microbiology, 9. doi:10.3389/fmicb.2018.00840