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:…genes identified to play a specific role in the development of peptidergic neurons was dimmed (dimm), which encodes a basic helix–loop–helix transcription factor that is required for the differentiation of diverse peptidergic neurons (Hewes et al. 2003; Park et al. 2008; Hamanaka et al. 2010).
Category: