1. Department of Physics; Acharya Nagarjuna University; Nagarjuna Nagar Guntur 522 510 Andhra Pradesh India
2. Department of Physics; Krishna University - Nuzvid Campus; Nuzvid 521 201 Andhra Pradesh India
3. Department of Physics; Kakani Venkata Ratnam College; Nandigama 521 185 Andhra Pradesh India
4. Institute of Physics; J. Dlugosz University; Ul. Armii Krajowej 13/15 Czestochowa 42-201 Poland