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:Our results show that dynein arms are apparently intact after elastase treatment, whereas trypsin induces fragmentation of the HCs, as has previously been reported (Ogawa, 1973; Ow et al., 1987; Inaba, 2000).
Category: