Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:As expected for a proline-rich glycoprotein, we have shown that these proteins contain various repeats of the decapeptide POVEKPOVYK and that the amino acid sequence of their amino terminal ends is the same, except for the fourth residue (García-Gómez et al. 2000).
Category: