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:The majority of oceanographic variables included in the model calculations are taken from the Regional Ocean Modeling System (ROMS) model coupled with the CoSiNE (Carbon, Silicate and Nitrogen Ecosystem) model (Chai et al., 2002, 2009; Dugdale et al., 2002a; Liu and Chai, 2009a, b).
Category: