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:Vitamin A supplementation in malnourished children reduces the severity of diarrheal disease (4), malarial morbidity (5), measles (6, 7), and mother-to-child transmission of HIV (8).
Category: