References:

• Haas J, Park EC, Seed B. Codon usage limitation in the expression of HIV-1 envelope glycoprotein. Curr Biol. 1996; 6 (3):315-24. / pmid: 8805248
• Kozak M. An analysis of 5'-noncoding sequences from 699 vertebrate messenger RNAs. Nucleic Acids Res. 1987; 15 (20):8125-48. / pmid: 3313277