Elementary & Secondary School Enrollment: Fall 1970-2008. US Department of Education.
Citazione stile Chigago Style (17a edizione)Elementary & Secondary School Enrollment: Fall 1970-2008. US Department of Education.
Citatione MLA (9a ed.)Elementary & Secondary School Enrollment: Fall 1970-2008. US Department of Education.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.