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:While Masek et al. (1994) called for an orographic precipitation control on the overall shape of the Beni basin, Safran et al. (2005) did
not find explicit correlations between erosion and climate with the existing data sets.
Category: