1. ^{{cite journal | vauthors = Lee PT, Hsu AY, Ha HT, Clarke CF | title = A C-methyltransferase involved in both ubiquinone and menaquinone biosynthesis: isolation and identification of the Escherichia coli ubiE gene | journal = Journal of Bacteriology | volume = 179 | issue = 5 | pages = 1748–54 | date = March 1997 | pmid = 9045837 | pmc = 178890 | doi = 10.1128/jb.179.5.1748-1754.1997 }}
2. ^{{cite journal | vauthors = Young IG, McCann LM, Stroobant P, Gibson F | title = Characterization and genetic analysis of mutant strains of Escherichia coli K-12 accumulating the biquinone precursors 2-octaprenyl-6-methoxy-1,4-benzoquinone and 2-octaprenyl-3-methyl-6-methoxy-1,4-benzoquinone | journal = Journal of Bacteriology | volume = 105 | issue = 3 | pages = 769–78 | date = March 1971 | pmid = 4323297 | pmc = 248499 }}
3. ^{{cite journal | vauthors = Dibrov E, Robinson KM, Lemire BD | title = The COQ5 gene encodes a yeast mitochondrial protein necessary for ubiquinone biosynthesis and the assembly of the respiratory chain | journal = The Journal of Biological Chemistry | volume = 272 | issue = 14 | pages = 9175–81 | date = April 1997 | pmid = 9083048 | doi = 10.1074/jbc.272.14.9175 }}
4. ^{{cite journal | vauthors = Barkovich RJ, Shtanko A, Shepherd JA, Lee PT, Myles DC, Tzagoloff A, Clarke CF | title = Characterization of the COQ5 gene from Saccharomyces cerevisiae. Evidence for a C-methyltransferase in ubiquinone biosynthesis | journal = The Journal of Biological Chemistry | volume = 272 | issue = 14 | pages = 9182–8 | date = April 1997 | pmid = 9083049 | doi = 10.1074/jbc.272.14.9182 }}