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:This assumption is confirmed by the different pattern of the expression of X linked genes in different parts of the same placenta: equally probable, mostly from one homolog, and fully monoallelic (Moreira de Mello et al., 2010).
Category: