The University of Pittsburgh has a fantastic Latin American collection-see Latin American Resources @ Pitt: Eduardo Lozano Latin American Collection.
A rich resource containing all types of materials, many appropriate as primary sources. You can search the description of items (author's name, title, subject headings) as well as the full text of materials. Items that are outside copyright protection will be displayed in full text. Items are from all countries, in many different languages. Filters allow you to limit to language, date of publication, etc. Items can be downloaded by logging in with your Andrew user ID and password.
The resources listed here are not the only ones available. Many others are in print or microform and can be found by searching library catalogs, like the CMU library catalog or Worldcat, a database of library holding thoughout the world (though mainly U. S.). Use some of these terms combined with your topic:
personal narratives
diaries
sources
correspondence
interviews
pamphlets
speeches
early works to 1800
For example:
women and diaries
slavery and "early works"
Holocaust and "personal narratives"