Worldwatch paper - Worldwatch Institute (Washington, D.C. : Worldwatch Institute, 1999)
UKM: no. 146 (1999)- no.152-154, no.155-159, no.146-149, 157-159 (hantar jilid pada 2/5/07) b.17-20
Keywords: Human ecology; Conservation of natural resources; Energy conservation; Power resources