Answer:
The encyclopedia and the chapter about the battle in a book called Great Battles of the Civil War.
Step-by-step explanation:
These are the two sources that would be considered secondary. A primary source is one that is an eyewitness to a particular event. Therefore, these types of sources were developed by people who were present at the event shortly after it occurred. On the other hand, secondary sources are those that provide interpretations based on primary sources.