As a rule of thumb, cross-references and URLs (Web links) in this ebook are hot, meaning you can click them to open their associated pages. Two caveats:
In Mac OS X 10.6 Snow Leopard's Preview, clicking a longer URL may not work. To avoid this bug, try clicking the end of the URL.
In an iPhone app, the convention for following a link is that you touch the link (meaning you hold down on it for several seconds) until it highlights. Once a highlight shows, release your finger and the page will load. If your iPhone app does not support hot links, or if certain links are not working, please contact us at firstname.lastname@example.org for advice.