توثيق جمعية علم النفس الأمريكية APA (الطبعة السابعة)
Helldén, U. (1987). An Assessment of woody biomass, community forests, land use and soil erosion in Ethiopia: A feasibility study on the use of remote sensing and GIS-analysis for planning purposes in developing countries. Univ.Pr.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)
Helldén, Ulf. An Assessment of Woody Biomass, Community Forests, Land Use and Soil Erosion in Ethiopia: A Feasibility Study on the Use of Remote Sensing and GIS-analysis for Planning Purposes in Developing Countries. Lund: Univ.Pr, 1987.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)
Helldén, Ulf. An Assessment of Woody Biomass, Community Forests, Land Use and Soil Erosion in Ethiopia: A Feasibility Study on the Use of Remote Sensing and GIS-analysis for Planning Purposes in Developing Countries. Univ.Pr, 1987.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.