For context, I'm a third year University student writing my dissertation on Florence's military actions during the Italian Wars. I'm already using Guicciardini and Machiavelli extensively in my study, but am failing for find similar primary sources discussing the later events of the wars.
So my question is, are there any primary sources in English available that cover the later Italian Wars or the war of Siena?
Any suggestions of sources are welcome.
NOTE: I'm doing fine for secondary sources, it is PRIMARY sources I'm struggling with.
Unfortunately, I'm not aware of much in the way of printed or digitized primary sources, certainly not in English. You might try looking at the documents digitized from the Archivio di Stato di Firenze by the Medici Archive Project.
The search function is pretty good, so you might find something. My research is on a later period, so I'm not certain how early the digitized documents go. You can also try the Biblioteca Nazionale Centrale di Firenze (BNCF). They have digitized a number of their documents, too.
Good luck!