APA استشهاد

Spiegel, H. W. (1961). Current economic problems (3.).

استشهاد بنمط شيكاغو

Spiegel, Henry William. Current Economic Problems. 3. Richard D Irwin, Inc, Illinois, 1961.

MLA استشهاد

Spiegel, Henry William. Current Economic Problems. 3. 1961.