(1968). Populations: A science unit for the primary grades (Trial ed.). Science Curriculum Improvement Study.
Lua i Stíl Chicago (17ú heag.)Populations: A Science Unit for the Primary Grades. Trial ed. Berkeley, CA: Science Curriculum Improvement Study, 1968.
Lua MLA (9ú heag.)Populations: A Science Unit for the Primary Grades. Trial ed. Science Curriculum Improvement Study, 1968.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.