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:Such works have been conducted in the fruit fly (Drosophila melanogaster) [12], the tsetse fly (Glossina morsitans morsitans) [8], and the yellow fever mosquito (Aedes aegypti) [13,14].
Category: