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:However, among the additional genes from the microarray that are upregulated by EBF activity we found lhx9 and lmo4, which are homologous to apterous, a known target of Collier in Drosophila [17].
Category: