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:…2000; Wang et al. 2001; Boddaert et al. 2003; Ceponiene et al. 2003; Jansson-Verkasalo et al. 2003; Rapin and Dunn 2003; Rosenhall et al. 2003; Boddaert et al. 2004; Gervais et al. 2004; Kasai et al. 2005; Kujala et al. 2005; Lepisto et al. 2005, 2006; Korpilahti et al. 2006; Tharpe et al. 2006).
Category: