Trager, Frank N.
Why Vietnam?
Frederick A. Preager, 1966
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Youngseon Jo
why? music
Elex Media Komputindo, 2013
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Cho, Youngsun
Why? drone
Elex Media Komputindo, 2019
 Buku Teks SO
Ross, Alf
Why Democracy ?
Harvard University Press, 1952
 Buku Teks SO
Jo, Youngsun
Why? Music
Gramedia, 2013
 Buku Teks SO