Brown, L. R., Flavin, C., Renner, M., & Starke, L. (1999). Vital signs 1999: The environmental trends that are shaping our future. W.W. Norton.
Lua i Stíl Chicago (17ú heag.)Brown, Lester Russell, Christopher Flavin, Michael Renner, agus Linda Starke. Vital Signs 1999: The Environmental Trends That Are Shaping Our Future. New York: W.W. Norton, 1999.
Lua MLA (8ú heag.)Brown, Lester Russell, et al. Vital Signs 1999: The Environmental Trends That Are Shaping Our Future. W.W. Norton, 1999.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.