University of Illinois (Urbana-Champaign campus). Elementary-School Science Project & University of Illinois (Urbana-Champaign campus). Elementary-School Science Project. (1962). Astronomy (Rev. ed.). University of Illinois, Elementary School Science Project.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)University of Illinois (Urbana-Champaign campus). Elementary-School Science Project و University of Illinois (Urbana-Champaign campus). Elementary-School Science Project. Astronomy. Rev. ed. Urbana, Ill.: University of Illinois, Elementary School Science Project, 1962.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)University of Illinois (Urbana-Champaign campus). Elementary-School Science Project و University of Illinois (Urbana-Champaign campus). Elementary-School Science Project. Astronomy. Rev. ed. University of Illinois, Elementary School Science Project, 1962.