1. Späth, Ernst. Die Naturlichen Coumarine. Ber. Deutchen Chem. Gesell.70A: 83–117. 1937.
2. —, K. Eiter, and T. Meinhart. Chroman und Coumaron-Ringschliisse bei einigen natürlichen Coumarinen. Ber. Chem. Gesell.75: 1623. 1942.
3. Cavallito, C. J. and H. E. Rockwell. Isolation of visnagan, the amorphous coronary dilator principle ofAmmi visnaga. Jour. Org. Chem.15: 821. 1950.
4. Schriner, R. L., and R. C. Fuson. The identification of organic compounds. 3rd ed. N. Y. pp. 52–57. 1948.
5. Call, T. G., and E. B. Fischer. Some pharmacological effects of the roots ofPteryxia terebinthina (Hook.) Coult. & Rose var.terebinthina,and of pteryxin, a substance isolated from the roots. Northwest Science32: 96–100. 1958.