I've now found all but one of my Warhammer books

The only one I cannot find anywhere is my Age of Sigmar 1st Edition Core Book. I know I have one, but it just doesn't seem to be anywhere, and it's driving me nuts not being able to find it. Hopefully this doesn't mean that I'll have to buy a new one because I don't think I could afford that.

I feel like I want to scream in frustration (I won't, but the pressure to do so in my chest is strong right now).