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 p35S::RPS4: GFP and the pABA2::ABA2 cassettes were transferred into the pHPT binary vector (Tzfira et al., 2005) or pMDC123 (Curtis and Grossniklaus, 2003) using LR clonase (Invitrogen), respectively.
Category: