1. Part of this work has been presented at the 20th Danish Crystallographic Meeting. – Part VIII see , , , and , Tetrahedron (submitted).
2. in Comprehensive Organic Chemistry (Edit. Bartin-Ollis-Haslam), first edition, vol 5, p. 247, Pergamon Press, 1979.
3. and in Specialist Periodical Reports. Amio-acids, Peptides, Proteins (Edit. Sheppard) vol. 8, p. 342 and p. 424, The Chemical Society, London 1976.
4. , and in Specialist Periodical Reports. Amino-acids, Peptides, and Proteins (Edit. Sheppard), vol. 9, p. 428, The Chemical Society, London, 1978.
5. E. R. Squibb and Sons, Inc. (Inv. , and ), US-Pat. 4234489 (Nov. 18, 1980)