Harmon, D. E. (2018). The early days of space exploration. Britannica Educational Publishing in association with Rosen Educational Services.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Harmon, Daniel E. The Early Days of Space Exploration. New York, NY: Britannica Educational Publishing in association with Rosen Educational Services, 2018.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Harmon, Daniel E. The Early Days of Space Exploration. Britannica Educational Publishing in association with Rosen Educational Services, 2018.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.