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:…firing rates of Purkinje cells are found in large parts of the cerebellum in cats, rabbits, and even primates (Chan et al. 1982; Eccles 1973; Frysinger et al. 1984; Lisberger and Fuchs 1978; Mano and Yamamoto 1980; Medina and Lisberger 2008; Miyashita and Nagao 1984; Yamamoto et al. 2007).
Category: