You may wish to quote a piece of work that has been referred to in something you have read. This is called ‘secondary referencing’ because you have not read the original piece of work. In other words, you are relying on the author you are reading to give a fair reflection of the contents of the original work.
Wherever possible, it is important to read the original work, but this may be difficult in some instances. If you must refer to a secondary reference, your text should make it clear that you have not read the original.
For example:
Research used by Smith (2000) regarding services marketing shows that the indicators formulated by Grant (1994) in his PhD thesis entitled Services marketing in transportation (Dunhill University) apply to the airline industry.
The work by Smith 2000 is included in your list of references because this is where you read about Grant’s research. However, the work by Grant (1994) is not included. You cannot include details about the original study, simply because you have not consulted it.