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:…et al. 2000; Hoey et al. 2003; Birkner et al. 2004; Rusu et al. 2005;
Kaushik et al. 2008), mouse (Autrup et al. 1978; Pretlow et al. 1978; Kondo et al. 1984; Kedinger et al. 1986; Fukamachi 1992, Macartney et al. 2000), rabbit (Benya et al. 1991; Hata et al. 1993; Reddy et al. 1996), pig…
Category: