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 addition, convergent studies (Langleben et al. 2001; Rubia et al. 2005; Silk et al. 2016; Team 2000) have reported that the pathophysiology of ADHD exhibits abnormalities in neural systems that are mainly related to cognitive control and motor functions.
Category: