Is there any information in his letter that he did not actually observe? How do you reconcile this fact with the idea that this is a primary source? Can a document be partially primary and partially secondary

The correct answer to this open question is the following.

Although the question is incomplete because it does not provide a specific reference about the author of the letter or any other reference, we can comment on the following.

A primary source is the piece of information that was written by a character or an individual that lived in the moment of the event, was part of the event, or witnessed the event. This individual could have written a letter, or a document -including a book. Or he/she took a photograph. Or was part of an interview. The secondary source includes information from a third person who was not part of the time or event but has found information through other resources. It is the case of an encyclopedia or researchers/historian books.

payments were made after the 1940s.

in the 1980s, a commission held investigations and made recommendations.