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:…ago from the mouse cerebellum (Furuichi et al., 1989), numerous inositol
trisphosphate receptor genes have been identified and grouped
into a family of transient receptor potential (TRP) channels
(Vannier et al., 1998; Blondel et al., 1993; Maranto, 1994; Ross
et al., 1992; Sudhof et al., 1991).
Category: