The answer is: provide formal citations for the sources.
When conducting research, a researcher needs to be careful to cite in a complete and proper way the information that other researchers have presented before and that he or she is now using. This is important for two main reasons: first, to avid plagiarism, and secondly, to allow other researcher to follow up on your sources for corroboration.
There are several ways to cite sources and they are called formatting styles (like MLA or APA). Depending on which one is being used, the researcher should stick to the guidelines of the style chosen.