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:In crustacean, apart from functioning as a digestive gland, hepatopancreas is also an important immune organ that functions as a primary site to synthesize and excrete immune molecules, such as beta-1,3-glucan binding protein (LGBP) [16], antibacterial peptide (AMP) [17], lectin or lectin related proteins and others [18].
Category: