(2001). Vocational Education Directory, 1971 [United States] / United States Department of Education. National Center for Education Statistics. [electronic resource].
Cita Chicago (17th ed.)Vocational Education Directory, 1971 [United States] / United States Department of Education. National Center for Education Statistics. [electronic Resource]. 2001.
Cita MLA (9th ed.)Vocational Education Directory, 1971 [United States] / United States Department of Education. National Center for Education Statistics. [electronic Resource]. 2001.
Atenció: Aquestes cites poden no estar 100% correctes.