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:We include treatment with an angiotensin-converting enzyme inhibitor and thiazide diuretic for those without CVD or cerebrovascular disease history, while including beta-blockers for those with such a history, as per WHO guidelines further detailed in Text S1 [16,25].
Category: