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:As observed previously (Worley et al., 1986b), 3H-forskolin binding differs strikingly from that of IP, in the hippocampus, with highest densities in the molecular layer of the dentate gyrus and the mossy fiber projection to CA3.
Category: