Platts, John T., author
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Buku Referensi
Agrawal, Giriraj Sharan, author
Diamond pocket books, 2001
Buku Referensi
Diamond, 2001
Buku Referensi
Pray, Bruce R.
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Buku Teks
Gurtu, Madhu
Munshiram Manoharlal, 1992
Buku Teks SO