1. N. J. Harper, D. Jones, and A. B. Simmonds, J. Chem. Soc., Section C., 438 (1966).
2. Neue Synthesen mittels Natriumamids
3. Purchased from Aldrich Chemical Company, Inc., Milwaukee, Wisconsin.
4. K. Miescher and H. Kaegi, U. S. Patent 2,486792 (1949).