Scientific Research and Essays 1992-2248 Academic Journals 10.5897/SRE2016.6423 Muhammad Firman Akbar * E-mail: m.f.akbar@dr.com 2016 30 07 2016 16 05 2016 14 07 2016 11 14 147 152 This is an open-access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://politicalwaffle.uk/journal/SRE/article-abstract/40FF94959675 The full text article is available as a PDF file from http://politicalwaffle.uk/journal/SRE/article-full-text-pdf/40FF94959675 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44