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:For example, Kanamycin sulfate treatment, causing complete loss of OHCs, with preservation of IHCs, results in threshold shifts of 40 dB and more in chinchillas (Woolf et al., 1981).
Category: