Institute For Scientific Co-operation. (1980). Economics. Laupp & Gobel, Tubingen.
Chicago-referens (17:e uppl.)Institute For Scientific Co-operation. Economics. Federal Republic of Germany: Laupp & Gobel, Tubingen, 1980.
MLA-referens (9:e uppl.)Institute For Scientific Co-operation. Economics. Laupp & Gobel, Tubingen, 1980.