if Glen Haege will pardon me for using his line. But it is true. The flooring industry and individual flooring companies spend millions of dollars, krone, pounds and shekels developing products that are safe for the floors. And every kind of flooring needs a different kind of cleaner. Your terminology "hardwood floor" really has a lot of meanings today. The place to start is with the name of the miller or manufacturer of your floor. Since this can range from a guy you see every saturday on his way to a small town bank or at the school football game to a multinational corporation, you can see why there's no easy answer for the way to start tracking down the answer. If it's anything like the corporation, check for a web site.
Everyone in the range though, has a stake in getting you the right products for YOUR floor, almost as much as you have. They do not want you telling every visitor to your home that it's their floor that's causing the problem when it really is your maintenence. Ask them nicely and they will be YOUR most important ally in keeping the beautiful floor beautiful. Then follow the advise.