Hi I am trying to create a bit of code that fits data points to a curve

right now I have

with(statistics):
NonlinearFit((   (A/2)/((B-r)^2+(A/2)^2)+C1+C2*r+C3*r^2),WEE,dde,r);

where WEE and dde are vectors containing the X and Y values respectively.

I was wondering if there was any way to set a range of values that the parameters can lie between

for instance 
0<A<1
and  -3<B<3

I was wondering how to build that into the code

F(x) is a Product: Maple