Graphis Poster 91 : the international annual of poster art.

MLA

Herdeg, W, and B.M Pedersen. Graphis Poster 91 : the International Annual of Poster Art. Zürich: Graphis Press, 1991.

APA

Herdeg, W., & Pedersen, B. (1991). Graphis Poster 91 : the international annual of poster art. Zürich: Graphis Press.

Chicago

Herdeg, W., and B.M Pedersen. Graphis Poster 91 : the International Annual of Poster Art. Zürich: Graphis Press, 1991.