reading tips?

Hi
I been working off and on, with making my own templets/themes.
now since i allways worked on such small prodjects i have managed. (with help ofcause)
Now this summer I was thinking of finaly read and learn not just try.
can some one recomend me some articles here ? a really good book since i read a couple and allways think i havent leard what i wanted.
I am really weak in PHP thought.

Thanks,,,, and ai hope everyone have a great summer
Lirys