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:…in substrate competence [Moglen and Bras, 1995], erosive efficiency due to sediment flux [Sklar and Dietrich, 1998] or to orographic precipitation [Roe et al., 2002], transient conditions [Snyder et al., 2000], and/or differential rock uplift rate [Kirby and Whipple, 2001] will impact actual…
Category: