Storz J, Page LA (1971). "Taxonomy of the Chlamydiae: reasons for classifying organisms of the genus Chlamydia, family Chlamydiaceae, in a separate order, Chlamydiales ord. nov". International Journal of Systematic Bacteriology21 (4): 332–334. doi:10.1099/00207713-21-4-332.
Everett K, Bush R, Andersen A (1999). "Emended description of the order Chlamydiales, proposal of Parachlamydiaceae fam. nov. and Simkaniaceae fam. nov., each containing one monotypic genus, revised taxonomy of the family Chlamydiaceae, including a new genus and five new species, and standards for the identification of organisms". Int J Syst Bacteriol49 (2): 415–40. PMID10319462. doi:10.1099/00207713-49-2-415.
Horn M, Collingro A, Schmitz-Esser S, Beier C, Purkhold U, Fartmann B, Brandt P, Nyakatura G, Droege M, Frishman D, Rattei T, Mewes H, Wagner M (2004). "Illuminating the evolutionary history of chlamydiae". Science304 (5671): 728–30. PMID15073324. doi:10.1126/science.1096330.
Teeling H, Lombardot T, Bauer M, Ludwig W, Glöckner F (2004). "Evaluation of the phylogenetic position of the planctomycete 'Rhodopirellula baltica' SH 1 by means of concatenated ribosomal protein sequences, DNA-directed RNA polymerase subunit sequences and whole genome trees". Int J Syst Evol Microbiol54 (Pt 3): 791–801. PMID15143026. doi:10.1099/ijs.0.02913-0.
Everett K, Bush R, Andersen A (1999). "Emended description of the order Chlamydiales, proposal of Parachlamydiaceae fam. nov. and Simkaniaceae fam. nov., each containing one monotypic genus, revised taxonomy of the family Chlamydiaceae, including a new genus and five new species, and standards for the identification of organisms". Int J Syst Bacteriol49 (2): 415–40. PMID10319462. doi:10.1099/00207713-49-2-415.
Rurangirwa F, Dilbeck P, Crawford T, McGuire T, McElwain T (1999). "Analysis of the 16S rRNA gene of micro-organism WSU 86-1044 from an aborted bovine foetus reveals that it is a member of the order Chlamydiales: proposal of Waddliaceae fam. nov., Waddlia chondrophila gen. nov., sp. nov". Int J Syst Bacteriol49 (2): 577–81. PMID10319478.
Horn M, Collingro A, Schmitz-Esser S, Beier C, Purkhold U, Fartmann B, Brandt P, Nyakatura G, Droege M, Frishman D, Rattei T, Mewes H, Wagner M (2004). "Illuminating the evolutionary history of chlamydiae". Science304 (5671): 728–30. PMID15073324. doi:10.1126/science.1096330.
Griffiths, E., Petrich, A., & Gupta, R. S. (2005) Conserved Indels in Essential Proteins that are Distinctive Characteristics of Chlamydiales and Provide Novel Means for Their Identification . Microbiology, 151: 2647-2657. PMID 16079343
Ward N, Rainey F, Hedlund B, Staley J, Ludwig W, Stackebrandt E (2000). "Comparative phylogenetic analyses of members of the order Planctomycetales and the division Verrucomicrobia: 23S rRNA gene sequence analysis supports the 16S rRNA gene sequence-derived phylogeny". Int J Syst Evol Microbiol50 (6): 1965–72. PMID11155969.
Teeling H, Lombardot T, Bauer M, Ludwig W, Glöckner F (2004). "Evaluation of the phylogenetic position of the planctomycete 'Rhodopirellula baltica' SH 1 by means of concatenated ribosomal protein sequences, DNA-directed RNA polymerase subunit sequences and whole genome trees". Int J Syst Evol Microbiol54 (Pt 3): 791–801. PMID15143026. doi:10.1099/ijs.0.02913-0.
Griffiths, E. and Gupta, R. S. (2007) Phylogeny and shared conserved insert in proteins provide evidence that Verrucomicrobia are the closest free-living relatives of the parasitic Chlamydiae. Microbiology, 153: 2648-2653. PMID 17660429