| Sources Name | Sources link | Description |
| Cogprints | http://cogprints.org | |
| InfoMine | http://www.infomine.com/ | Mining Intelligence and Technology |
| BASE | https://www.base-search.net/about/en/ | Bielefeld academic search engine |
| NPTEL | https://nptel.ac.in/ | |
| Wikipedia | https://en.wikipedia.org/wiki/Encyclopedia | The Encyclopedia |
| Indian Academy of Science | www.ias.ac.in/ |