What I read is what can teach me a better style of programming. A good book
for this is "Professional PHP Programming"
YES! That's my favorite "intermediate/advanced" book for PHP.
But the best "total beginner" PHP book, by far is:
The PHP4 Bible - by Tim Converse and Joyce Park
http://www1.fatbrain.com/asp/bookinfo/bookinfo.asp?theisbn=076454716X
It will walk your co-workers through easy-but-deep tutorials about every aspect of PHP, including many less-documented things like PHP4 Sessions.
(... and believe me - I've read ALL the PHP books out there. I learned PHP from scratch this year with NO programming experience at all.)