1. For reviews see:
2. , , in The Alkaloids (Ed.: ), Academic Press: New York, 1984 , 23, 157-223.
3. , , , in Alkaloids: Chemical and Biological Perspectives (Ed.: ), John Wiley & Sons: New York, 1987 , 5, 639-690.
4. , , , in The Alkaloids (Ed.: ), Academic Press: New York, 1998 , 51, 199-264.