(1968). Populations: A science unit for the primary grades (Trial ed.). Science Curriculum Improvement Study.
Chicago-referens (17:e uppl.)Populations: A Science Unit for the Primary Grades. Trial ed. Berkeley, CA: Science Curriculum Improvement Study, 1968.
MLA-referens (9:e uppl.)Populations: A Science Unit for the Primary Grades. Trial ed. Science Curriculum Improvement Study, 1968.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.