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:‚Ä¶TB abundances were expressed as total counts and not as CFU counts, but considering that a maximum of 10% of total marine bacteria are cultivable, our results are similar to those reported by Skjermo and Vadstein (1993) and Hach√© and Plante
 (2011) in their commercially enriched rotifer cultures.
Category: