Political Thought in the 16th Century
An overview of the Florentine thinkers. From the European Educational Project.
The Invasions of Italy, Machiavelli and Guicciardi
Chapter 4 of the book "Renaissance and Reformation" by William Gilbert. Discusses the political climate and the two major thinkers.
Virtù in and since the Renaissance
Jerrold E. Seigel writes about the concept and how it is used by Machiavelli and later thinkers. From the Dictionary of the History of Ideas.