[Maxima] problem with integration of gaussian distribution

[Riemann, Robert]

>> What must I do, to let Maxima sort some summands in powers of p?
>
>I'm sorry, I don't understand.

(any function f(p)) => (...)p^0+(...)p^1+(...)p^2+...

If I know the term (...) in front of p^0, i could substitute it to reduce the 
number of variables (in my case from 6 to 3)

I hope it is now clear, what I meant.

Greets.