Cita APA (7a ed.)

Helmer, O. (1983). Looking forward: A guide to futures research. Sage Publications.

Cita Chicago Style (17a ed.)

Helmer, Olaf. Looking Forward: A Guide to Futures Research. Beverly Hills, Calif [u.a.]: Sage Publications, 1983.

Cita MLA (8a ed.)

Helmer, Olaf. Looking Forward: A Guide to Futures Research. Sage Publications, 1983.