Signes vitals 1998
Worldwatch Institute
W. W. Norton & Company
Nova York, Londres, 1998

World Resources 1996-97. Una guia pel medi ambient mundial
World Resources Institute
Oxford University Press
Nova York, Londres, 1996

World Development Indicators 1998
The World Bank
Washington, 1998

Informe del desenvolupament humà 1998
PNUD - Programa de les Nacions Unides pel desenvolupament
Centre UNESCO de Catalunya
Barcelona, 1998
http://www.undp.org/hdro/

Indicators of Sustainable Development: Framework and Methodologies
Departament for Policy Coordination and Sustanaible Development
United Nations, 1996
gopher://gopher.un.org/00/esc/cn17/1996/backgrnd/INDICATO

Living Planet Report
WWF, 1999
http://www.panda.org/livingplanet/home.shtml

Monitoring Environmental Progress
The World Bank
Washington, 1995