How to cite

When an author was cited in another author’s text, but you can’t access the original, you can use indirect or so called secondary source citing. 
In the case of indirect citing, include both authors in the in-text reference. Examples in APA style:

In the reference list you should add only these items you actually read, in this case Smith (2018) and Ferguson (2019).
The indirect citing should be used only exceptionally, when the original work is not available. Never refer directly to a work you actually did not read.