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:For the non-smoothing solution not in H(1)(Ω), a element-local L2 projection technique was presented in [14] to deal with the nonconvex Lipschitz polyhedron with reentrant corners and edges.
Category: