This is a base class, all site-specific drivers should inherit its members
and methods. Driver subclasses named '$name' should be packaged as
WWW::Scraper::ISBN::$name_Driver, e.g. WWW::Scraper::ISBN::LOC_Driver for
LOC (Library of Congress) driver. Each driver need only implement the
search() method, though they may have as many other methods as they need to
get their job done. Only search() will be called by
WWW::Scraper::ISBN->search().

WWW: http://search.cpan.org/dist/WWW-Scraper-ISBN-Driver/