• Analysis of CO2 emission reduction options in the Estonian energy systemEsop, Markko-Raul; Liik, OlevBaltic electrical engineering review1998 / 1, p. 59-69: ill
• Estonian energy planning in the context of climate changeLiik, Olev; Esop, Markko-RaulProceedings of the Joint Seminar of the International Energy Agency and Energy Technology Systems Analysis Programme2000 / p. 297-313
• Estonian energy system and emissions modelling using markal modelEsop, Markko-Raul; Liik, Olev; Valdma, Mati; Landsberg, MartEconomics of greenhouse gas limitations : country study series : Estonia1999 / p. 127-168: ill
• Possible energy sector trends in Estonia : context of climate changeKask, Ilmar; Esop, Markko-Raul; Pallo, Toomas; Liik, Olev; Raesaar, Peeter; Selg, Vello; Valma, Arno; Kask, Ülo; Purju, Alari; Kallaste, Tiit1999 https://www.ester.ee/record=b1275146*est
• Prospects of wind generated electricity in Estonia calculated with Markal modelLiik, Olev; Esop, Markko-RaulProceedings of the International Energy Agency's Energy Technology Systems Analysis Programme : annex VII 5th Workshop2001 / p. 8
• The future of Estonian energetics : dependency on CO2 emission reductionEsop, Markko-Raul; Liik, OlevThe Baltic review1999 / p. 35-37, 52: ill
• Tuuleenergia konkurentsivõime ja CO2 emissioonide vähenemise analüüs Eestis mudeliga MARKALLiik, Olev; Esop, Markko-RaulTaastuvate energiaallikate uurimine ja kasutamine : teise konverentsi kogumik = Investigation and Usage of Renewable Energy Sources : second conference proceedings2001 / lk. 49-55 : ill