| 1 | Taylor & Francis Open Access |
| 2 | ELSEVIER |
| 3 | WILEY |
| 4 | SPRINGER |
| 5 | SPRINGER |
| 6 | SCIENCE DIRECT |
| 7 | JSTOR |
| 8 | OPEN ACCESS LIBRARY |
| 9 | Oxford Academic |
| 10 | LUND UNIVERSITY LIBRARIES |
| 11 | KARGER |
| 12 | THIEME OPEN |
| 13 | OMNICS OPEN ACCESS |
| 14 | BMC |
| 15 | MDPI |
| 16 | COGENT OA |
| 17 | OPEN ACCESS |
| 18 | ERUDIT |
| 19 | HIGHWIRE |
| 20 | DIRECTORATE OF OPEN SCIENCE ARTICLES |
| 21 | PLOS |
| 22 | PubMed |
| 23 | African Journal Online |
| 23 | Directory of Open Access Journal |
| 23 | BioOne Online JOurnal |
