1. Dale, J. (1973)Acta Chem. Scand. 27, 1115.
2. Hempel, A. (1978)Acta Cryst. B 34, 3454.
3. Hofheinz, W., Grisebach, H., and Friebolin, H. (1962)Tetrahedron 18, 1265.
4. Maier, R., Woitun, E., Wetzel, B., Reuter, W., Goeth, H., and Lechner, U. (1977) US Patent 4,048,306.
5. Main, P., Woolfson, M. M., and Germain, G. (1971) multan. A Computer Program for the Automatic Solution of Crystal Structures from X-ray Diffraction Data, University of York, England.