Each academic discipline creates and uses primary and secondary sources differently; the definition of a primary source only makes sense in the context of a specific discipline or field of inquiry.
In the humanities and the arts, a primary document might be an original creative work.
It might be a part of the historical record written about, or in proximity to, an event.
In the sciences, it might be a publication of original research.
Here are two definitions that try to capture the elusive nature of primary documents:
Consult databases of primary sources: three steps
See also: Primary Sources: Collections Available through Cornell, a Research Guide.
Gallica. Digitized archives from the French national library (Bibliotheque nationale de France, or BnF) and other French libraries. Rich in images.
These words and phrases are standard terms (metadata) used in many databases and library catalogs to signal primary sources.
So you might add one of these terms to your search. Thus: Haiti--History--Coup d'etat 1991 and add the subdivision "Personal narratives."
You are combining PLACE and TIME and SUBJECT and then TYPE OF SOURCE.
See Images: A Guide to Finding Visual Resources for essential practical guidance on finding, citing, and fair use of images.