The phrase 'letter asserting that' is correct and usable in written English.
It can be used when the writer is stating a fact or belief through a letter or other written form of communication. For example: In her letter asserting that the project had been successfully completed, the manager thanked the team for their hard work.
It fired off a letter asserting that district official misunderstood the court ruling.
The law, 3 U.S. Code section 15, allows for a challenge to electoral votes — either on an individual basis or statewide — if one member of the House and one member of the Senate submit a letter asserting that votes were not "regularly given".
AT&T filed its own letter, asserting that it was not consulted by Apple on the Google voice application.
Milbank Tweed was paid $970,000 for an opinion letter asserting that the plan would save gift and estate taxes and related legal work, according to court papers.
Signatories to the letter asserting that Britain is not a Christian country include Philip Pullman, Ken Follett, Prof Alice Roberts, Prof Harold Kroto and Sir Terry Pratchett.
Mr. Schrems said his group planned to send the Irish regulator a formal letter asserting that the regulator's audit of Facebook was unsatisfactory and allowed the company to operate in Europe without adhering to E.U. data protection law.
The lawmakers' letter asserts that "it was clearly never, as administration officials once insisted, the result of a popular protest".
(A museum? Inside a museum?) Dubbed the "L.A. Emale Action," the Guerilla Girls' letter asserts that, of the thirty artists in the show, ninety-seven per cent are white and eighty-seven percent are men.
The letter asserted that those policies were "doomed to failure".
They were answered by Mr. Fitzpatrick, who, in a letter, asserted that ABC did, indeed, test produce for pesticide residue.
The letter asserted that efforts to falsify maintenance and performance reports had been "going on for over two years".
