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:We elected to take this course because formal methods for analyzing the efficiency of move ordering strategies in the alpha-beta search are unreported in the literature [27, 30], and as a result, practical experimentation is the accepted form of analysis in the state-of-the-art [26].
Category: