1. H. L. WONG and S. M. WAHL, in ?Peptide growth factors and their receptors?, edited by M. B. Sporn and A. B. Roberts (Springer, 1990) p. 510.
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3. P. SANDFORD, in ?Chitin and chitosan?, edited by G. Skjakbraek, T. Anthonsen and P. Sandford (Elsevier Applied Science, 1989) p. 51.
4. C. J. BRINE, ibid. p. 679
5. B. CHITHAMBARA THANOO, M. C. SUNNY and JAYAKRISHNAN, J. Pharm. Pharmacol. 44 (1991) 283.