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:1b, left panel), previously described in detail (e.g. Rouiller et al. 1998; Liu and Rouiller 1999; Schmidlin et al. 2004; Freund et al. 2006,
2009; Kaeser et al. 2010, 2011): briefly, the tests were performed on a perspex board (10 cm 9 20 cm) containing 50 randomly distributed slots, each filled…
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