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:A number of studies have reported similar conclusions (Dauncey 1990; Esparza et al. 2000; Johannsen and Ravussin 2008; Levine 2004; Levine et al. 1999, 2001a; Schoeller 2001).
Category: