APA 7th Edition Citation Guide
Secondary Source/Indirect Citation (as cited in)

A secondary source (also known as an indirect citation) is used when the ideas of one author are published in another author’s text but you have not read or accessed the original author’s work.

Generally, it is best to access the original source for the information and cite that source.

If you cannot access the original source, use these steps to give proper credit: 

• In the reference list, provide the details of the work in which you found the quotation or idea (this work is considered the secondary source).
• For the in-text citation, include the author and year of both the original and secondary sources. Add "as cited in" between the sources in the in-text citation. For example, (Smith, 2015, as cited in Jonson, 2019).

Reference Page Example:

Jonson, S. (2019). On the origin of sin. Penguin Books. 

In-text Citation Examples:

Smith (2015, as cited in Jonson, 2019) believes that...

...(Smith, 2015, as cited in Jonson, 2019).