Walling, D. R. (1995). At the threshold of the millenium. Phi Delta Kappa Educational Foundation.
Chicago-viite (17. p.)Walling, Donovan R. At the Threshold of the Millenium. Indiana: Phi Delta Kappa Educational Foundation, 1995.
MLA-viite (9. p.)Walling, Donovan R. At the Threshold of the Millenium. Phi Delta Kappa Educational Foundation, 1995.
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