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:‚Äö√Ñ¬∂amount of antibiotics in wastewater and/or in ponds by fish farmers without regulations and/or in agriculture These finding are similar to those of (Kusuda and Sugiyama, 1981) who showed that Staphylococcus epidermidis which present in the aquatic environment originated from water (or fish) rather‚Äö√Ñ¬∂
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