how to use the word "sources"
the extraction of information from appropriate reference sources .
can l delete sources in this sentence. what is different between them?

Question

how to use  the word  "sources"
the  extraction  of information from appropriate reference sources   .
      can l   delete  sources in this sentence. what is different between  them?

Answer

Yes, you can. You just have to make reference plural --> references.

reference sources --> reference acts as a modifier on the noun sources
references --> reference is used as a noun meaning the same thing

In this context, there is no difference between "reference sources" and "references".