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:Our results from the constitutive Mecp2 KO mice present the first in vivo verification of a progressive shift in cortical E/I balance favoring inhibition, which is consistent with earlier brain slice studies (Dani et al., 2005; Nelson et al., 2006; Wood et al., 2009; Wood and Shepherd, 2010).
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