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:This session also helps to decrease the number of trials in the formal TMS sessions since the critical SSD does not then have to be obtained during the TMS trials and there is then a better chance to observe the effects of TMS (see also Chambers et al., 2007).
Category: