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:Although previous studies from this laboratory have demonstrated that neutrophils are capable of detecting pulsed weak (10 4 V/m) electric fields (Kindzelskii and Petty 2000; Rosenspire et al. 2001) as well as applied magnetic fields (Rosenspire et al. 2003), the early mechanistic steps in field…
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