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:Six classifiers, E1, E2, E3, E4, E5, E6, are used for the recognition experiments of the unconstrained handwritten numerals from Concordia University [10] and the University of California, Irvine (UCI) [1].
Category: