Citing from an author who is citing another author is known as using a secondary source. It should be used rarely. You must always try to read the original work, known as the primary source. However, if you are forced to cite a secondary source because you cannot consult the original work, you have to cite the original as contained in the secondary source. Your in-text citation must include both authors: the author(s) of the original source and the author(s) of the secondary source. For example: (Habermehl, 1985, as cited in Kersten 1987). In your reference list you should provide the details of the secondary source (the source you read). In this example: the details of Kersten 1987. Most author-date citation styles do not include the primary source (the source you did not read) in the reference list. However, with the numeric styles details of both the primary and secondary source may be included in the reference list.