The phrase "as a supplementary source" is correct and usable in written English.
It can be used when referring to an additional resource that provides extra information or support to the main content.
Example: "The report was well-researched, and I included several articles as a supplementary source to enhance the findings."
Alternatives: "as an additional resource" or "as a supporting reference".
Islam holds that the Qurʾān alone contains revelation in the strict sense (waḥy), but it accepts tradition (Hadith) as a supplementary source of Islamic law (Sharīʿah).
Moreover, it is shown that the combination systems are capable to produce hydrogen gas at high efficiency which can be used as a supplementary source for green energy thus minimizing the entire process cost.
Instead of the textbook being the primary tool used for learning with the lecture as a vehicle, and Web or hard copy references used as a supplementary source of knowledge; the Web is now the primary source of current and relevant knowledge and the book and the lecture becoming secondary.
Thus, the anthropogenic activities appear as a supplementary source of F− to its further elevation in the groundwater.
Their use as a supplementary source is possible when further information or confirmation is needed from other sources.
As a supplementary source, some of the material covered in the class can be found in Riemannian Geometry by Gallot, Hulin, and Lafontaine, and Smooth Manifolds by Lee.
For these artists, Set.fm is meant to be a supplementary source of revenue, as well as a way to keep connected with fans.
In this way, QSAR models can be used both as an alternative and a supplementary source of information.
Rather than taking them at face value or as gospel, datasets may often serve as an indicative springboard, a starting point or a supplementary source for understanding a topic.
The ingluvies, despite having a very low cyanogenic content, serve as a convenient, supplementary source of sugar to the children who can include this resource as a seasonal delicacy at minimum risk.
If made of clean, low-carbon materials and with a discount for burning in company furnaces, they could provide a lucrative revenue stream as well as a supplementary power source.
