(Order of authorship in the original publication: Woese, Kandler, Wheelis.) Introduction of the three-domain biological classification system that divides cellular life into three forms or domains: Archaea, Bacteria, and Eukarya.  Archaea and bacteria are prokaryotic microorganisms, or single-celled organisms, the cells of which have no nucleus. The  Eukarya domain includes all life that has a nucleus and membrane-bound organelles, and multicellular organisms

(Thanks to Juan Weiss for this reference and its interpretation.)

Digital facsimile from pnas.org at this link.