Nice post. I learn something new and challenging on sites I stumbleupon everyday. It's always useful to read through content from other authors and use something from other sites.

INDEXED BY:

         

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

CSRID Journal Editor's Office:

Universitas Potensi Utama. Jl. K.L. Yos Sudarso Km 6,5 No.3-A Telp. (061) 6640525 Ext. 214 Tanjung Mulia Medan 20241