Thought I'd posted this in the USPS Postal Regulations form - mea culpa! Now in its proper place.

You need to contact your local PO and/or carrier ASAP.  The sooner the better, as the more time passes, the less likely they will remember the package, or be able to track down where it went. 

I had one "delivered" to my post office box.  The sender had DC on it, so I knew it said delivered, but there wasn't any notice in my box.  I went to the counter and asked for it and they found it.  Maybe, if you can't find out where it actually was delivered, they have it behind the counter somewhere and forgot to actually deliver it.

I posted under your USPS thread.  Hope your book turns up Tracy!