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 lower bound on 2 is derived in Weinstein and Weiss (1984a, 1984b) as the Ziv–Zakai lower bound ( ZZLB
2 ) and has been adapted in elastography by Varghese and Ophir (1997a) as:
ZZLB 2
sT 2
6T T , BTSNRc
Threshold1, BTSNRc
2 BB
2
T T , BTSNRc Threshold2, BTSNRc
2 CRLB
2
T T , BTSNRc.
(3)
Here, B…
Category: