Qt project management - bigger project

[Peppy]

I am very confused how to manage bigger project in Qt with .pro files. I have got this directory tree:

/
/bin   - all binary files (.EXE/.DLL)
/lib    - all linking libraries (.a/ .lib) 
/tmp  - temporary 
/src   - sources
Projects:
/src/Executable/Executable.pro
/src/Library.GUI/Library.GUI.pro
/src/Library.Services/Library.Services.pro
/src/...

/
/bin   - all binary files (.EXE/.DLL)
/lib    - all linking libraries (.a/ .lib) 
/tmp  - temporary 
/src   - sources
Projects:
/src/Executable/Executable.pro
/src/Library.GUI/Library.GUI.pro
/src/Library.Services/Library.Services.pro
/src/...

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How to link this projects together with Qt .pro/.pri (projects files) ? Is there some tutorial for it?