1. A. S. Shashkov, V. I. Grishkovets, O. Ya. Tsvetkov, and V. Ya. Chirva, Khim. Prir. Soedin., 571 (1993).
2. Z. Kasprzyk and Z. Wojciechowski, Phytochemistry,6, 69 (1967).
3. S. Subramanian and A. Bax, J. Magn. Reson.,71, 325 (1967).
4. G. A. Morris and R. Freeman, J. Magn. Reson.,29, 433 (1978).
5. V. Ya. Chirva, T. V. Sergienko, V. I. Grishkovets, and A. A. Loloiko, Rast. Resurs.,26, No. 1, 104 (1990).