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:
Jonson, S. (2019). On the origin of sin. Penguin Books.
Smith (2015, as cited in Jonson, 2019) believes that...
...(Smith, 2015, as cited in Jonson, 2019).