Cite a Secondary Source Correctly in APA and Harvard

You want to cite a study you've only seen quoted inside another book, and getting that wrong looks careless. This shows the correct secondary-source citation in both APA and Harvard, so you credit the original without pretending you read it. For students who keep finding the perfect quote second-hand and don't know how to attribute it honestly.

I need to cite a secondary source, a work I have not read directly but found quoted or referenced within another source I have read.

Original (primary) source:
Author: {PRIMARY_AUTHOR}
Year: {PRIMARY_YEAR}
Title: {PRIMARY_TITLE}

Source where I encountered it (secondary source):
Author: {SECONDARY_AUTHOR}
Year: {SECONDARY_YEAR}
Title: {SECONDARY_TITLE}

Using both APA 7th edition and Harvard style:
1. Write the correct in-text citation for using this secondary source
2. Show what appears in the reference list and what does not
3. Explain the underlying rule about why only the secondary source is listed
4. Warn me of two common mistakes students make when citing secondary sources

End with a brief note on when it is acceptable to rely on a secondary source versus tracking down the original.