1. http://www.jetir.org/papers/JETIR1805348.pdf
2. www.jetir.org/papers/JETIR1805245.pdf
3. www.ijcrt.org/papers/IJCRT1813010.pdf
4. www.ijcrt.org/viewfull.php?&p_id=IJCRT1813018
5. http://www.ijcrt.org/papers/IJCRT1892499.pdf
6. http://www.ijcrt.org/papers/IJCRT1892501.pdf
7. http://www.ijirmps.org/research-paper.php?id=151