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:Finding a serum -hCG level greater than the discriminatory zone, in combination with an indeterminate ultrasonography, has been shown to be associated with ectopic pregnancy.(8,9) Typical transvaginal discriminatory zone values in the literature range from 1,500 to 3,000 mIU/mL and have largely been developed according to radiology-performed ultrasonography in outpatients,(10) with intrauterine pregnancy defined as the visualization of a gestational sac.
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