"Further confirmation" refers to additional evidence or proof that supports an existing belief or statement. It means obtaining more information or facts to increase confidence or make something more certain. Full definition
Both offered the same cautious message about the need to wait for further confirmation of economic strength before lifting rates from zero. (foreignpolicy.com)
Likewise, other physicists are waiting for further confirmation before getting too excited. (sciencenews.org)
This result provides further confirmation of previous observational studies that had suggested the existence of such a link. (sciencedaily.com)