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:Those with alcohol dependence ever in lifetime met at least three symptoms of maladaptive pattern of alcohol use leading to clinically significant impairment or distress (Sheehan et al., 1998; American Psychiatric Association, 2000).
Category: