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:These findings are
similar to the reports of Horswell (1991), and Ugar and Semb (2001), while they differ from the reports of Sandham (1986), Hoening and Schoener (1992), Giannakari (2004), Rajion et al. (2006), and Lima et al. (2009).
Category: