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:Indeed, compounds such as methyl benzene, ethylbenzene, 1-octene, xylenes, styrene and 1,4 dichlorobenzene have been found in packaged food (Lau and Wong 2000; Nerì et al. 2002).
Category: