1. D. Clark, H.M. Powell, A.F. Wells, J. Chem. Soc., 642–645 (1942)
2. M.J. Taylor, L.A. Woodward, J. Chem. Soc., 4670–4672 (1963)
3. B. Meyer, Chem. Rev. 76, 367–388 (1976)
4. Y. Yamamura, H. Saitoh, M. Sumita, K. Saito, J. Phys.: Condens. Matter 19, 176219 (2007)
5. F. London, Trans. Faraday Soc. 33, 8–26 (1937)