Megorden, H. T. (1967). 1967-69 handbook of free science materials: With related areas: life science, earth science, physical science, space and universe, health, transportation, communication, conservation (New ed.). Educational Publications.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Megorden, Herbert T. 1967-69 Handbook of Free Science Materials: With Related Areas: Life Science, Earth Science, Physical Science, Space and Universe, Health, Transportation, Communication, Conservation. New ed. Moorhead, Minn: Educational Publications, 1967.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)Megorden, Herbert T. 1967-69 Handbook of Free Science Materials: With Related Areas: Life Science, Earth Science, Physical Science, Space and Universe, Health, Transportation, Communication, Conservation. New ed. Educational Publications, 1967.