1. E. Späth. Ber., 70, 83 (1937).
2. L. Reppel. Die Pharmazie, no. 9, 272, 1954.
3. G. V. Pigulevskii and G. A. Kuznetsova, ZhOKh, 24, no. 12, 2174, 1954.
4. G. A. Kuznetsova, collection: Plant Raw Materials, [in Russian] vol. 5, 21, 1955.
5. G. K. Nikonov, DAN SSSR, 156, 1210, 1964.