Näsholm, T. (1991). Aspects of nitrogen metabolism in Scots pine, Norway spruce and birch as influenced by the availability of nitrogen in pedosphere and atmosphere. Swedish University of Agricultural Sciences, Dept. of Forest Genetics and Plant Physiology.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Näsholm, Torgny. Aspects of Nitrogen Metabolism in Scots Pine, Norway Spruce and Birch as Influenced by the Availability of Nitrogen in Pedosphere and Atmosphere. Umeå: Swedish University of Agricultural Sciences, Dept. of Forest Genetics and Plant Physiology, 1991.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Näsholm, Torgny. Aspects of Nitrogen Metabolism in Scots Pine, Norway Spruce and Birch as Influenced by the Availability of Nitrogen in Pedosphere and Atmosphere. Swedish University of Agricultural Sciences, Dept. of Forest Genetics and Plant Physiology, 1991.