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:In addition, sequences homologous to the cao-2 (Saelices et al. 2007) and ylo-1 (Estrada et al. 2008) genes for the Wnal steps to neurosporene are present in the sequenced genome from P. anserina (Espagne et al. 2008).
Category: