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:Haemaphysalis longicornis ticks have been reported to be associated with the transmission of SFTSV (Sun et al. 2014; Jiang et al. 2012; Yu et al. 2011).
Category: