Specific Rules #4 for Place of Publication (required) to Citing Entire Reports Vancouver Style: No place of publication can be found

If no place of publication can be found on the title page or its verso (back), but one can be found elsewhere in the publication or can be reasonably inferred (e.g., Washington as the place for a publication of the Department of Health and Human Services), place the city in square brackets, such as "[Washington]".

[Deakin West (Australia)]: National Rural Health Alliance (AU); 1998 Feb. 74 p.

If no place of publication can be found or inferred, use [place unknown].

[place unknown]: Western Health Foundation; 1985.

Según:

Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers [Internet]. 2nd edition. Chapter 4: Scientific and Technical Reports

Related:

General Rules for Place of Publication (required) to Citing Entire Reports Vancouver Style

Specific Rules #1: Non-US cities

Specific Rules #2: Joint publication

Specific Rules #3: Multiple places of publication

Specific Rules #4: No place of publication can be found

Examples for Place of Publication (required) to Citing Entire Reports Vancouver Style