The phrase "a firmly documented" is correct and usable in written English.
It can be used when referring to something that is well-supported by evidence or records, often in academic or professional contexts.
Example: "The research findings are based on a firmly documented study that provides clear evidence of the results."
Alternatives: "well-documented" or "thoroughly recorded".
In the lower urinary tract, TRPV1 expression is now firmly documented not only in a large subpopulation of nerve fibers but also in nonneuronal tissues.
American cornetist who was a vital link between the semimythical prehistory of jazz and the firmly documented history of jazz proper.
"It is firmly documented that when people have significant capital gains, a small part of them do induce an increase in consumption," Mr. Greenspan said.
King Oliver, byname of Joseph Oliver (born May 11 , 1885 Abend, La., U.S. died April 8 , 1938 Savannah, Ga ., American cornetist who was a vital link between the semimythical prehistory of jazz and the firmly documented history of jazz proper.
But no firmly documented chronology of rulers, reigns and conquests -- of the sort that exists for ancient Egypt and Mesopotamia -- actually goes back beyond 841 B.C. "This has been a major regret for Chinese history and world history," said Li Xueqin, a prominent historian, today at a news conference to disclose the results of the project.
Although the first two LP's for Capitol re-created his previous hits in the then-new high fidelity medium, the remainder of James's output from this association firmly documented what Mr. Teachout described as his "completely retooled... ensemble style".
The fingerprint of global warming has been firmly documented in the shift toward extreme precipitation already observed in the northern hemisphere.
[ 32] These gradients are firmly documented in the industrialized world.
In this patient, N. transvalensis infection was firmly documented by culture and subsequent sequence-based identification.
A recent review [ 16] listed 201 chemicals known to be neurotoxic in humans; only 5 of these substances have been firmly documented as causes of developmental neurotoxicity.
