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:…of the HD-Zip I and II families function as developmental regulators, specifically being involved in regulation of developmental adaptation to environmental stress conditions (e.g. Meijer et al. 1997; Lee and Chun 1998; Scarpella et al. 2000, 2002; Manavella et al. 2006; Komatsuda et al. 2007).
Category: