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:The present results using Long Evans rats are consistent with previous reports that MIA during pregnancy does not alter classical fear conditioning in the adult male offspring of either Wistar (Zuckerman and Weiner, 2005) or Sprague Dawley rat strains (Vorhees et al., 2012; Yee et al., 2012).
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