Names with apostrophe's

Hello,
I could use some help here.  I have an entry in the MySQL, that use an
apostrophe,  for example lets call it "O'Reilly".  I have added
addslashes to my insert statement so MySQL accepts it with out
complaining.

The problem I am having is I use this information "O'Reilly" in a GET
URL somewhere else in the site.
For example here's my link:
echo("<td><a
href='user_book_results_detail.php?book=$row[book]>$row[book]</a></
td>");

When I mouse over and view the URL, PHP thinks the apostrophe (single
quote) is the end and quits.   I know I need to include a back slash or
escape this character  but I am not entirely sure how I do it?
Suggestions?

Sample URL:
http://user_book_results_detail.php?book=O