Goog literature on advaced php

[CybJunior]

Hi,
I know the basics of php, created lots of sites with admin panels etc. But every time i do something new i find a new and better way to improve it. Everything i do now is not optimized chaotic etc.

Is there any kind of literature that may help improve the knowledge, not just teach the basics?

Thanks a lot,

Alexey

[NogDog]

Zend Developer Zone has many useful articles and tutorials you might want to browse. OReilly.com has lots of PHP books for various levels of expertise.