(1973) Current Perspectives on Social Problems, Third, Belmont, California: Wadsworth Publishing Co., გვ. 2. ISBN0-534-00289-7. „Culture is the "social heritage" of society. It includes the complex set of learned and shared beliefs, customs, skills, habits, traditions, and knowledge common to the members of society. Within a culture, there may be subcultures made up of specific groups that are somewhat separate from the rest of society because of distinct traits, beliefs, or or interests.“
„Birth Rate Chart“(GIF). CNN. CNN. 2011-08-11. ციტატა: „Annotated Chart of 20th Century US Birth Rates“
yale.edu
Churney, Linda (1979). „Student Protest in the 1960s“. Yale-New Haven Teachers Institute: Curriculum Unit 79.02.03. ციტატა: „This unit focuses on student protest in the 60s“
