[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990
     Phylum "Proteobacteria" Garrity et al. 2005 see Superphylum Proteobacteria Craig et al. 2010
       Class Gammaproteobacteria Garrity et al. 2005
         Order "Enterobacteriales" Garrity and Holt 2001 nom. nud.
           Family Enterobacteriaceae Rahn 1937 (Approved Lists 1980)
             Genus Citrobacter Werkman and Gillen 1932 (Approved Lists 1980)
               01 Citrobacter freundii (Braak 1928) Werkman and Gillen 1932 (Approved Lists 1980)
               02 Citrobacter amalonaticus (Young et al. 1971) Brenner and Farmer 1982
               03 Citrobacter braakii Brenner et al. 1993
               04 Citrobacter farmeri Brenner et al. 1993
               05 Citrobacter gillenii Brenner et al. 2000
               06 Citrobacter koseri Frederiksen 1970 (Approved Lists 1980)
               07 Citrobacter murliniae Brenner et al. 2000
               08 Citrobacter rodentium Schauer et al. 1996
               09 Citrobacter sedlakii Brenner et al. 1993
               10 Citrobacter werkmanii Brenner et al. 1993
               11 Citrobacter youngae Brenner et al. 1993