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 one recent study using the tractography applying constrained spherical deconvolution to investigate a total of 43 patients
with ADHD, Silk et al. (2016) found a significant lateralization to the left for fractional anisotropy (FA, a DTI measurement) in the putamen tracts.
Category: