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:These results are similar to those reported by ElHawarry (2012) using O. aureus 9 O. niloticus hybrids and Mateen and Ahmed (2007) for 17a-MT hormone treated O. niloticus.
Category: