Secondary references are where one author quotes the work of another, but you do not have access to the original source
Example within the text:
Buzan (1974 cited in Barnes 1992) says that a good summary of a lecture is often more useful than writing extensive notes
Example of a book reference:
Barnes, R. (1992) Successful study for degrees. London: Routledge.
Other references follow the same format of the resource in front of you. i.e. if it is from a webpage reference the webpage, for a journal reference the journal etc.