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:Such MAC algorithms and universal hash functions include UMAC [9], MMH [17], NMH [17], Square Hash [15], Poly1305-AES [6], CWC [25], GCM/GMAC [30, 31], and a recent polynomial variant by Bernstein [7].
Category: