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:In view that PFD changes mouse liver glutathione S-transferase (mGST), glyceraldehyde-3-phosphate dehydrogenase, carbonic anhydrase III and Zn superoxide dismutase (CuZn-SOD) contents [42, 47, 48], we wished to explore whether it affects other cellular antioxidative enzymes.
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