1. von Baeyer A (1885) Ber Dtsch Chem Ges 18:2269
2. March J (1992) Advanced organic chemistry, 4th edn. Wiley, New York, pp 150–161
3. Cox JD, Plicher G (1970) Thermochemistry of organic and organometallic compounds. Academic, London
4. Baulder M, Hahn J, Clef E (1984) Z Naturforsh 39b:438
5. Iwamoto T, Tamura M, Kabuto C, Kira M (2000) Science 290:504