and other such entities are not allowed in epubs unless you have a suitable DOCTYPE declared at the top of the file. Here is an example of the beginning of a .xhtml file that uses   in the text and passes epubcheck:
Code:
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">