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:Anamnesis was structured according to ICCS recommendations [1, 2] and followed by a complete clinical examination, completion of sleep disorders questionnaires (Berlin Questionnaire, Children’s Sleep Disorders Scale and Epworth Scale) [18–20], evaluation of balance and completion by patients and their caregivers of a quality of life questionnaire [Pediatric Quality of Life Inventory version 4.
Category: