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:Similar observations were also made by other authors, including DRAGAN [5], SCHMALZRIED, JASTY, HARRIS [20], VASU, CARTER, and HARRIS [22], WALL, DRAGAN [23], and WALL [24].
Category: