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Sykes B.Sykes B.Philos Trans R Soc Lond B Biol Sci. 1999 Jan 29;354(1379):131-8; discussion 138-9. doi: 10.1098/rstb.1999.0366.Philos Trans R Soc Lond B Biol Sci. 1999.PMID: 10091253Free PMC article.