RT Journal Article SR 00 A1 Nakicenovic, N. A1 Labys, C. T1 Energy Strategies for a Carbon-Free Future JF Siemens Review (R&D Special) YR 1995 FD 1995 VO Fall IS 1995 SP 4 OP 6 PB Siemens AG LK https://pure.iiasa.ac.at/id/eprint/4399/