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:Dead individuals were removed, surface sterilized with 5.2% sodium hypochlorite, rinsed twice with sterile water, and plated on potato dextrose agar to confirm that mortality was due to infection by M. anisopliae (Rosengaus et al. 1998).
Category: