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:The prevalence of disturbed behaviors or emotional maladaptations in different groups of children with CP have been reported to be from 30-80% (Denhoff & Holden, 1954; Graham & Rutter, 1968b; Hourcade & Parette, 1984; McDonald, 1987; Rosenbloom, 1971; Storrow & Jones, 1960).
Category: