Reck, H. U. On Friendship. Philosophical Reflections on an Economy of Giving and a Style of Expenditure: Hans Ulrich Reck. Sciences of the interface : proceedings of the International Symposium Sciences of the Interface, ZKM, Center for Art and Media, Karlsruhe Germany, May 18-21, 1999.(2001).
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Reck, Hans Ulrich. "On Friendship. Philosophical Reflections on an Economy of Giving and a Style of Expenditure: Hans Ulrich Reck." Sciences of the Interface : Proceedings of the International Symposium Sciences of the Interface, ZKM, Center for Art and Media, Karlsruhe Germany, May 18-21, 1999.(2001) .
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Reck, Hans Ulrich. "On Friendship. Philosophical Reflections on an Economy of Giving and a Style of Expenditure: Hans Ulrich Reck." Sciences of the Interface : Proceedings of the International Symposium Sciences of the Interface, ZKM, Center for Art and Media, Karlsruhe Germany, May 18-21, 1999.(2001), .