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:All four infants had multi-organ dysfunction syndrome [3]; their underlying diagnoses were complex congenital heart disease (two infants), left ventricular non-compaction cardiomyopathy, and congenital dyserythropoietic anemia, respectively.
Category: