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 this study, compared with the control group, there were no significant differences in the level of P in the 2.5 mg and 5 mg letorzole treated groups, consistent with other results [Fatemi et al. 2008; Garcia-Velasco et al. 2009; Wang et al. 2013].
Category: