مؤلف: Emrul Hasan

The work was done by Zuned Ahmed, Md Emrul Hasan and Dr. Sujaul Chowdhury ([email protected]) as two separate M.S. theses in 2013 in Department of Physics, Shahjalal University of Science and Technology: http://www.sust.edu, Sylhet 3114, Bangladesh. Dr Chowdhury is a faculty of the Department; he has a glorious record of academic, scientific, teaching and research achievements; details in http://schowdhury-phy.weebly.com/.