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:Significant inhibition of CaM kinase II activity has been observed in many models of delayed neuronal cell death including whole animal models of ischemia (Taft et al., 1988; Churn et al., 1990b, 1992a; Zivin et al., 1991; Aronowski et al., 1992) and glutamate excitotoxicity in neuronal cultures (Churn et al.
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