Secondary source

The book you are using is your primary source. If this book refers to another source and you wish to use this part of the text in your work, that becomes a secondary source. Whenever possible, try to find the original source. You may inadvertently be citing another author’s mistake. If you really cannot locate the original source, then reference the secondary source.

In brackets, indicate the source by providing the original author’s name and using the words ‘cited in’. Give the secondary author’s name along with the year of publication and the page number of the original reference. Conversely, reference the original author of the primary source in the text and provide the appropriate parenthetical citation.

In this example below, Brown is the primary source and author of the book you are using and Smith is the secondary source quoted in Brown:

Students often make mistakes with this and just copy the secondary sources as given in the primary text. This is plagiarism.