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:The isolation vocalizations of infant mice are used as behavioral markers of stress (Rupniak et al., 2000) or disease state (Ricceri et al., 2007; Scattoni et al., 2008; Young et al., 2010; Wohr et al., 2011a).
Category: