Fiser, A., Simon, I. and Barton, G. J. (1996),
"Conservation of amino acids in multiple alignments: Aspartic acid has unexpected conservation", FEBS Lett.,
Russell, R. B., Copley, R. R. and Barton, G. J. (1996),
"Protein fold recognition by mapping predicted secondary structures",J. Mol. Biol.,259(3)
A PostScript preprint for A4 paper is available here.