1. Department of Physics, S. V. Degree College, Kadapa, Andhra Pradesh, India;
2. Department of Humanities and Basic Sciences, G. Pulla Reddy Engineering College (Autonomous), Kurnool, Andhra Pradesh, India;
3. Department of Physics, JNTUA College of Engineering, Pulivendula, Andhra Pradesh, India;
4. Department of Physics, SKR & SKR Government Degree College for Women (Autonomous), Kadapa, Andhra Pradesh, India