1. Robertson, J.M.: Nature 134 (1934) 138.
2. Struchkov, Yu.T., Khotsyanova, T.L., Kitaigorodsky, A.I.: Zh. Fiz. Khim. 27 (1953) 1330.
3. Robertson, J.M., White, J.G.: J. Chem. Soc. (1947) 1001.
4. Pochan, J.M., Shoemaker, R.L., Stone, R.G., Flygare, W.H.: J. Chem. Phys. 52 (1970) 2478.
5. Poquet, E., Pacault, A., Hoarau, J., Lumbroso, N., Zanchetta, J.: Compt. Rend. 250 (1960) 706.