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The formulae are written in MathML and are best viewed if using a browser that supports MathML (without messing up the html-document-type); preferably Firefox.

You need Java to view an applet. Some web browsers (Firefox and Google Chrome) show a warning if the latest version of Java is not installed. If you have several versions of Java installed, you will get the warning until the older versions are uninstalled.

If it is red, you can click on it!

The applets have none or few explanations, this is as intended.