It is always best to read the original or primary sources, but sometimes this is difficult if the original work was published in another language or was published in a book that is difficult to obtain. In such a case, you would need to cite the original or primary source in the text of the paper, but you would provide a reference in the reference list for the secondary source. Also, it is important to remember that APA says to " 'use secondary sources sparingly, for instance, when the original work is out of print, unavailable through usual sources, or not available in English.' When the original work, the speech, is available through a 'usual source,'' sources that can be retrieved through ordinary publishing channels should be cited.
See also: The APA Style website's FAQ posting on how to format a secondary source.
Ex. 1: Quote by one author used in the text of another book: Within the Text
a. Secondary citation within the text:
According to Freud (as cited in Skinner, 1923), the characteristics ….
b. The document used is cited in the reference list
Skinner, B. F. (1974). About behavioralism. New York, NY: Knopf.