extensions

I wish to access native functionality in a native library from php. I believe writing a php extension is the way to go about it. (The lib I want to access is sufficiently complex that doing a system call to execute it isn't a viable solution) Can anyone point me to some useful guide? I've found the following links on the web: http://www.devnewz.com/2002/0909.html http://www.devarticles.com/art/1/170/4 http://www.geocrawler.com/mail/msg.php3?msg_id=2695523&list=5 http://php.weblogs.com/discuss/msgReader$2403 http://www.php.net/manual/en/zend.php http://www.qandr.org/~quentinsf/phpmodule/ http://www.derickrethans.nl/ze-ext/talk.html http://www.zend.com/zend/api.php http://www.php.net/manual/en/zend.possibilities.builtin.php but maybe someone knows of a really useful resource for this that I've missed? thanks, alex