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 Cross Entropy (CE) Method: CE (Rubinstein and Kroese, 2004) is an iterative method whose goal is to optimize a function f parameterized by a vector θ ∈ Θ by direct search in the parameter space Θ. Figure 7 contains the pseudo-code of the CE algorithm used in our experiments (Szita and Lőrincz, 2006; Thiery and Scherrer, 2009b).
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