(2000). Percentage Distribution of 6- to 12-year-olds, 1972-97. U.S. Department of Education.
Cita Chicago (17th ed.)Percentage Distribution of 6- to 12-year-olds, 1972-97. U.S. Department of Education, 2000.
Cita MLA (9th ed.)Percentage Distribution of 6- to 12-year-olds, 1972-97. U.S. Department of Education, 2000.
Atenció: Aquestes cites poden no estar 100% correctes.