Find the missing field before completing the reference
An absent date or DOI is not an invitation to guess. Verify the work type and primary record first, then use the missing-information rule for the required style. The records below are fictional and are not real publications.

1. Check author, date, title and source separately in the work and the publisher’s record. A website footer’s copyright year need not be the publication date of the particular work.
2. If no date is available, use the required style’s no-date notation instead of replacing it with the current year. Keep your access note separate. The target journal may require a different language or style adaptation.
3. Include a DOI only when verified for that work in the original or publisher record. Do not borrow one from a similar title. “DOI not found” is different from establishing that none exists.
4. Check the in-text citation and reference together. For a missing author or title, use the style’s applicable example. If the source itself cannot be found, do not invent fields to make it look like a real publication.

Fictional record A: Organisation: Example Research Unit; title: Open data note; date: not found; source: training record. No real institution or publication is claimed.
Correction A: APA’s English examples use n.d. for no date. Check the target publication’s adaptation; do not guess 2026.
Fictional record B: Author and year present; DOI unverified. Check the publisher record rather than generating an identifier; keep the verification result in a working note.
Two separate dates: Publication date: the date stated for the work. Access date: when you opened the record. They are not the same field.
Checking card: Work type __; author __; date/missing field __; title __; source __; verified DOI/URL __; access note __; target style __; open question __.

Fictional record A: ____________________
Correction A: ____________________
Fictional record B: ____________________
Two separate dates: ____________________
Checking card: ____________________
Use this card to inspect a reference manager’s output too. Correct punctuation does not prove that a source exists or supports the claim you are making.

APA Style — missing information — https://apastyle.apa.org/style-grammar-guidelines/references/missing-information