^ abcdefde Groot, Raoul J.; et al. (2009). "Revision of the family Coronaviridae"(PDF). International Committee on Taxonomy of Viruses (ICTV). p. 18. Archived(PDF) from the original on 7 February 2019. Retrieved 23 January 2020. A new species, Betacoronavirus 1, is proposed to accommodate previously established Betacoronavirus species of humans, cattle, swine and horses (Human enteric coronavirus; Human coronavirus OC43; Bovine coronavirus; Porcine hemagglutinating encephalomyelitis virus; Equine coronavirus) and a newly recognized virus of dogs (canine respiratory coronavirus; Erles et al., 2007)
^ICTV 5th Report Francki, R. I. B., Fauquet, C. M., Knudson, D. L. & Brown, F. (eds)(1991). Classification and nomenclature of viruses. Fifthreport of the International Committee on Taxonomy of Viruses. Archives of Virology Supplementum 2, 452 pp. https://ictv.global/ictv/proposals/ICTV%205th%20Report.pdf[1]
^"Virus Taxonomy: 2018b Release"(html). International Committee on Taxonomy of Viruses (ICTV). March 2019. Archived from the original on 4 March 2018. Retrieved 23 January 2020.
. In all members of Betacoronavirus subgroup A, a haemagglutinin esterase (HE) gene, which encodes a glycoprotein with neuraminate O-acetyl-esterase activity and the active site FGDS, is present downstream to ORF1ab and upstream to S gene (Figure 1).
. The presence of HE genes exclusively in members of Betacoronavirus subgroup A, but not members of Betacoronavirus subgroup B, C and D suggested that the recombination had probably occurred in the ancestor of members of Betacoronavirus subgroup A, after diverging from the ancestor of other subgroups of Betacoronavirus.
