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:HT = medical treatment of moderate hypertension; CAB = coronary artery bypass; Hemodial = hemodialysis; L Transp = liver transplantation; HIV = medical treatment of human immune virus infections [8].
Category: