edited by Mac E. Van Valkenburg and Wendy M. Midleton
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Stallings, William, author
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Buku Teks
Skees, William D.
Lifetime learning , 1981
Buku Teks
edited by S. Ramani
North Holland, 1981
Buku Teks
Stalling, William, author
Maxwell Macmillan International, 1991
Buku Teks