Can anyone tell me how to prove the Inverse Gaussian distribution belongs to the exponential family? I've shown it with both the Poisson and the exponential distribution itself, but am struggling with the Inverse Gaussian being more complicated.

For anyone that doesn't know, it takes the form:

f(y)=(sqrt(2*pi*ф*(y^3)))*exp(-((y-µ)^2)/(2*pi*(µ^2)*y)) where y,ф,µ >0

Many thanks,

Shaun