References
- Kreher , R. and Seubert , J. 1965 . Z. Naturforschg. , 20b : 75
- White , J. D. and Mann , M. E. 1969 . Advances in Heterocyclic Chemistry , Vol. 10 , 113 New York, N. Y. : Academic Press Inc. .
- Kreher , R. and Seubert , J. 1966 . Tetrahedron Lett. , : 3015