The phrase "a third source for" is correct and usable in written English.
It can be used when referring to an additional origin or reference point for information, data, or materials.
Example: "In my research, I found a third source for the historical data that supports my thesis."
Alternatives: "an additional source for" or "a supplementary source for".
A third source for the continuing allure of the Ballets Russes is sex.
Mr. Emrich said that Union and other counties also maintain their own open-space funds, and that New Jersey's Green Acres program could be a third source for acquisition money.
A third source for speed profiles is the train's existing odometry measurements, and the research in this area is typically focused on real-time train location for signalling or automatic train protection.
Over the last decade, text mining, big-data analysis, social media, and search engine data have given birth to a third source for obtaining measures of investor sentiment.1.
Private and public hospitals might have served as a third source for case finding, but they are not obligated to report cases of M. ulcerans, and their record-keeping systems are such that abstracting cases would be very difficult.
Under a third set of guidelines, bloggers would pledge to get a second source for any gossip or breaking news they write about.
It's a pretty good practice to find a second source for its claims – though that is more difficult than it seems, since the second source has frequently lifted its information unchecked from Wikipedia.
Sadly, MPs did not ask him why his reporters had failed to obtain a second source for any of those far-fetched and malicious stories obtained through anonymous leaks.
They are rapidly becoming a second source for middle-income customers.
The surfaces of iron oxyhydroxides can store significant amounts of sulfate and protons and serve as a second source for prolonged contamination.
This intensity is insufficient to create a rise in the water level leading to a concentrated recharge that would be a second source for the nappe.
