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:…protagonists (referents), different visual supports (without text) can be employed including cartoon videos (e.g., Arnold et al., 2009) or picture booklets (e.g., Hickmann et al., 1995; Van der Lely, 1997; Colle et al., 2008; Hendriks et al., 2014; Kuijper et al., 2015; Contemori andDussias, 2016).
Category: