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:This has been demonstrated for neural sources that are known to be highly correlated, such as bilateral activation of the temporal lobes during steady-state auditory stimulation (Brookes et al., 2007; Dalal et al., 2006; Popescu et al., 2008; Quraan and Cheyne, 2008; Quraan and Cheyne, 2010), and for primary visual sources (Quraan and Cheyne, 2008; Quraan and Cheyne, 2010), and is likely the case for many other sources as most brain modules are organized with bilateral symmetry.
Category: