Where i can download sourse code?

Hello, sorry for such weird question, but i am looking for all day…
I want to download source code of APM:Plane 3.4v to work with it throught Arduino IDE, like it shows here - http://ardupilot.org/dev/docs/building-ardupilot-with-arduino-windows.html?highlight=apm
I found link only for Copter firmware at the previous page, but it doesnt exist anymore…
Thank you very much…