For example, if you are borrowing a quotation of Smith's work, which is cited in Jones, but you did not read Smith's work:
In-text
Name the original source in the sentence, and provide an in-text citation for the secondary source. Include the words as cited in to indicate that you are citing a quotation:
According to Smith's research (as cited in Jones, 2003, p. 12)...
Reference
Include the source you actually read in your references list. If you read Jones, but not Smith, include Jones in your references list.