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:Springer
Instruments
Data collection consisted of a questionnaire packet composed of three parts: demographic questions, a modified version of the Conflict Tactics Scales (CTS) (Straus, 1979), and a modified version of the Domestic Violence Self-Labeling Scale (DVSLS) (Hamby & Gray-Little, 2000).
Category: