Dorling Kindersley Limited. (2015). When on Earth?: History as you've never seen it before (First American edition.). DK Publishing.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Dorling Kindersley Limited. When on Earth?: History as You've Never Seen It Before. First American edition. New York, New York: DK Publishing, 2015.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Dorling Kindersley Limited. When on Earth?: History as You've Never Seen It Before. First American edition. DK Publishing, 2015.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.