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:Finally, MG624 (a selective antagonist for the chick a7 homomeric receptor) binds the chick a7 subtype with a Ki of 106 nM (Gotti et al., 1998; Maggi et al., 1999), but the Ki of its binding to native a6 receptors is 40 times higher.
Category: