Spieth, D. A. (2011). All that happened had to happen: Walter Bortolossi / Text by Darius A. Spieth ; published by Louisiana State University School of Art. Louisiana State University Press.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Spieth, Darius A. All That Happened Had to Happen: Walter Bortolossi / Text by Darius A. Spieth ; Published by Louisiana State University School of Art. Baton Rouge: Louisiana State University Press, 2011.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Spieth, Darius A. All That Happened Had to Happen: Walter Bortolossi / Text by Darius A. Spieth ; Published by Louisiana State University School of Art. Louisiana State University Press, 2011.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.