| ACTRN Identifier | actrn |
| Archival Resource Key | ark |
| Bibcode | bibcode |
| ClinicalTrials.gov Identifier | nct |
| DRKS Identifier | drks |
| Digital Object Identifier | doi |
| EU Clinical Trials Register | euctr |
| EU Persistent URL | data.europa.eu |
| European Patent Office application ID | epo_id |
| GRID | GRID |
| GSK Identifier | gsk |
| Geographic Location-Password Scheme | GeoPass |
| Global Biodiversity Information Facility | GBIF |
| HAL / Hyper Article en Ligne identifier | hal |
| Handle | handle |
| ISRCTN Identifier | isrctn |
| Ichushi | ichushi |
| International Standard Name Identifier | ISNI |
| JPRN Identifier | jprn |
| Microsoft Academic Graph Identifier | mag_id |
| NII Article ID | NAID |
| NII Citation ID | NCID |
| Open Archives Initiative | oai |
| Open Researcher and Contributor ID | orcid_pending |
| Open Researcher and Contributor ID | orcid |
| OrgReg | OrgReg |
| PANGAEA | PANGAEA |
| Participant Identification Code | PIC |
| Patent application number in EPODOC format | epo_nr_epodoc |
| Protein Data Bank Identifier | pdb |
| PubMed Central ID | pmc |
| PubMed ID | pmid |
| RNSR | RNSR |
| ROR | ROR |
| Registry of research data repositories | re3data |
| Research Resource Identifier | RRID |
| RingGold | RingGold |
| UNKNOWN | UNKNOWN |
| Virtual International Authority File | VIAF |
| WHO Identifier | who |
| arXiv | arXiv |
| info:eu-repo/dai | info:eu-repo/dai |
| orcid workid | orcidworkid |
| urn | urn |
| w3id | w3id |