I don't know how to explain, but here is a source about it. I hope somebody has a better explanation. cái này nghe có tự nhiên không?

Then I would say this: "I don't know how to explain it/this better, but here is the original source. I hope somebody has a better explanation."

I added "it" or "this" after "I don't know how to explain", because "explain" needs an object when used this way.

I also added the word "better", because "I don't know how to explain (this)" alone means that you are 100% unable to explain it. But since you wrote a paragraph, you can explain is somehow; maybe just not very well.

"Original source" describes that page where the information was "originally" present before you rephrased it. You could also say "the source of the information" or simply "its source".