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:There are also several other reports of isolation of Cronobacter (from neonatal intensive care units where Cronobacter infections have occurred) and other members of Enterobacteriaceae from reconstituted PIF (Caubilla-Barron & Forsythe 2007; Cawthorn et al. 2008).
Category: