Table 3: Digital libraries selected and initially retrieved results.
| Database Name | URLs | Initially Retrieved | |
| 1 | ACM Digital Library | http://dl.acm.org/ | 637 |
| 2 | Science Direct | http://www.sciencedirect.com/ | 62 |
| 3 | Scopus | https://www.scopus.com/ | 2196 |
| 4 | IEEE Xplore | http://ieeexplore.ieee.org/ | 342 |
| 5 | Web of Science | https://webofknowledge.com/ | 71 |
| 6 | Springer Link | http://link.springer.com/ | 1273 |
| Total number of papers | 4581 | ||