The phrase "a more reliable source" is correct and usable in written English.
You can use it when comparing the trustworthiness or accuracy of different sources of information.
Example: "Before making a decision, it's important to consult a more reliable source to ensure the information is accurate."
Alternatives: "a more trustworthy source" or "a more credible source."
Try to find a more reliable source to back up the story.
The battery could be used to make sporadic renewable power a more reliable source of electricity for the grid.
This enlightened self-interest, underpinned by a sense of national solidarity, is a more reliable source of mutual support than charitable contributions.
Experts say this would reduce the need to build large fossil-fuel-burning power plants, which are still needed to provide a more reliable source of power.
Sri Lanka's impressive rag-makers, operating in high-value niches, may find China a more reliable source of fabric than corrupt, rowdy Pakistan.
The German economy, which has been less affected by the debt crisis, has helped make retail banking a more reliable source of profit than investment banking.
The local Jerry's Seafood chain stopped using Chesapeake Bay crabmeat years ago in favor of a more reliable source of blue crabmeat from Venezuela.
Off-grid electricity generation using renewable energy technologies has become a more reliable source to fulfill the needs of rural areas at limited level without considering conventional resources.
Anthony Codling at said Parsons Brinckerhoff was "the jewel in the crown", as the consulting trade is seen as a more reliable source of income, compared with the more volatile construction business.
Nearly everyone started off wary but then became keen to talk and grateful that someone was suggesting a way to cut through the packs of shouting politicians to a more reliable source of information.
Retail banking — the branch down the street where you have your checking account — is a more reliable source of profits, Roger Martin says, than the billion-dollar deal-making of investment banks.
