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Copyright @2017. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium 

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Hak Cipta @ 2017. Ini adalah artikel akses terbuka yang didistribusikan di bawah ketentuan Lisensi Internasional Creative Commons Attribution-NonCommercial-ShareAlike 4.0 (http://creativecommons.org/licenses/by-nc-sa/4.0/) yang memungkinkan penggunaan non-komersial tanpa batasan digunakan, distribusi dan reproduksi dalam media apa pun.