 Phylogenetic structure of the prokaryotic domain: the primary kingdoms by Carl R. Woese and George E. Fox

PNAS74(11),5088–5090(1977). Primary record pmc.ncbi.nlm.nih.gov/articles/PMC432104/ ; author full names directly verified from original-paper byline in university-hosted scan bip.weizmann.ac.il/education/course/evogen/Phylogenetics/woese.pdf . Abstract: phylogenetic distinction based on ribosomal-RNA sequence characterization. Do not describe the1977 experiment as a modern PCR amplicon survey.