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:…hippocampus for episodic encoding and retrieval processes in healthy young subjects was initially proposed as part of the HIPER model, with the anterior part of the hippocampus being preferentially involved in encoding, and retrieval mainly depending on its posterior portion (Lepage et al., 1998).
Category: