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:The spectroscopic results described above parallel closely those reported earlier for C-phycocyanin and its subunits by Glazer et al. (1973), who showed that the long wavelength absorption band of the trimeric and hexameric forms of the protein arises as a consequence of interactions between the chromophores of different monomers, rather than of interactions between chromophores within the cq~ monomer.
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