SEAMEO Regional Language Centre, 1982
Buku Referensi
Schunk, Dale H., author
Pearson Education, 2010
Buku Teks
Fraenkel, Jack R., 1932-2014, author
McGraw-Hill, 2012
Buku Teks
David Ward, Kathleen Scaler Scott, editor
Psychology Press, 2011
Buku Teks
John C. Smart
Springer, 2012
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