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:Lamotrigine monotherapy (50–200 mg daily) was also reported to be superior to placebo in the treatment of nonrapid cycling bipolar I depression in adults and uncontrolled observations have suggested possible antimanic [19,20], antidepressant [21], and anticycling/mood stabilization properties [13,19,22].
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