This is called secondary referencing. First, we recommend that you try to locate and read the primary source – this will make it much easier to reference, and will ensure you are not taking the quote/paraphrase out of context.

Situation A: you can’t find the primary source

You reference both primary and the secondary source in your final bibliography. You then also refer both sources in your footnote, for example (see footnote below):

The study by the University of Warwick, cited in Bryson and MacKerron2, found a clear correlation between the productivity of employees and their happiness.

2 Andrew J. Oswald, Eugenio Proto, and Daniel Sgroi, quoted in Alex Bryson and George MacKerron, ‘Are you happy while you work?’, The Economic Journal, 127 (2015), 106-125 (p. 124) [accessed 4 August 2021].

Situation B: you can find and use both primary and secondary source

You reference both the primary and secondary sources in your footnotes and bibliography independently as you would any other reference.