主題:Sex in marriage|20th century.|History|United States ; Marriage|20th century.|History|United States ; Sex customs|20th century.|History|United States
主題:Sex in marriage|20th century.|History|United States ; Marriage|20th century.|History|United States ; Sex customs|20th century.|History|United States
主題:Malaria|20th century.|History|South Asia ; Malaria|Prevention.|South Asia ; Malaria|Control|South Asia. ; Social Sciences, general. ; Human Geography. ; Public Health/Gesundheitswesen. ; Environmental Health. ; Physical Geography.