Only Attribute Your Source
There will be times when an author will quote another author. You can use the quotation or a paraphrase from the other author, if you locate the original source and see if for yourself. If you can't locate the original source, do not cite it as your source because even careful authors can make a mistake. And, unfortunately, there are authors who make up data.
When you cite a source, you say that you actually saw the material where you said you found it. For example, in this tutorial I quote from Barbara K. Stripling's "Learning-Centered Libraries: Implications from Research." Because I have not read this article, I list the reference as:
Stripling, Barbara K. "Learning-Centered Libraries: Implications from Research." School Library Media Quarterly 23.3 (1995): 163-170. Cited in Lathrop, Ann and Kathleen Foss. Student Cheating and Plagiarism in the Internet Era. Englewood, CO: Libraries Unlimited, 2000.