This Canadian site has a lot of good information about the differences between various countries' culture and the culture of Canada. Since the culture of the United States is very similar, it works well for our purposes.
PAY ATTENTION TO THE UNCERTAINTY AVOIDANCE INDEX in particular which measures how the average member of a culture feels about a certain amount of risk. That level is different across cultures. Tolerance of risk and uncertainty affects many business decisions.
This encyclopedia "covers more than 500 cultural groups in Asia and Oceania, Europe, the Americas and Africa. Five volumes — organized for quick reference by continent — cover history, politics, customs, religion, education, gender issues (new to 2nd edition!) and much more for culture groups such as Kurds, Amish, Germans and others."
From the publisher: "The most authoritative and comprehensive text of its kind, Kiss, Bow, or Shake Hands, 2nd Edition is your must-have guide to proper international business protocol. With countries such as China and India taking on a more significant role in the global business landscape, you can't afford not to know the practices, customs, and philosophies of other countries."