1. Bronson, G.: In,“Wall Street Journal”, December 6, p. 23 (1976)
2. Budzikiewicz, H., Djerassi, C., Williams, D. H.: In: Mass Spectrometry of Organic Compounds, p. 329, Holden-Day, San Francisco: 1967
3. Chang, S. K., Harrington, G. W.: Anal. Chem. 47, 1857 (1975)
4. Druckrey, H., Preussmann, R., Ivankovic, S., Schmahl, D.: Z. Krebsforsch. 69, 103 (1967)
5. Eisenbrand, G., Spaczynski, K., Preussmann, R.: J. Chromatogr. 47, 304 (1970)