1. J. L. Hirshman andT. S. Ma, Mikrochim. Acta [Wien]1968, 262.
2. J. L. Hirshman, P. W. Zimmerman, andT. S. Ma, Mikrochim. Acta [Wien]1968, 1085.
3. A. I. Scott, The Interpretation of The Ultraviolet Spectra of Natural Products, Table 2.6. Oxford: Pergamon Press. 1964.
4. F. W. McLafferty, Interpretation of Mass Spectra. New York: W. A. Benjamin. 1966. p. 33.
5. D. H. Williams andI. Fleming, Spectroscopic Methods in Organic Chemistry, Table 4-1 B. London: McGraw-Hill. 1966