Writing this project effectively begins with reading your sources effectively. This writing project necessitates taking notes: your December self is not going to remember what your September self thought or read.
While many of your sources may be dealing with similar events or historical happenings, the researchers will likely differ in their interpretation of the significance of certain events or may choose to understand those events through different contexts. To lay the foundation for being able to write, you may want to use the following:
When reading: Look for areas of overlap between sources to locate the differences and areas of agreement. What is the significance of those differences?
When note-taking: It’s all about topics and sub-topics. Because you are synthesizing sources (that is bringing them together) you will be limited if you follow a source’s organizational strategy; instead, you should find topics and sub-topics that will allow you to, as much as possible, write about more than one source.