APA aipamena

(2004). Signposts 2004: Essential data, timelines, and analyses of global trends. Worldwatch Institute.

Chicago Style aipamena

Signposts 2004: Essential Data, Timelines, and Analyses of Global Trends. Worldwatch Institute, 2004.

MLA aipamena

Signposts 2004: Essential Data, Timelines, and Analyses of Global Trends. Worldwatch Institute, 2004.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.