What is the name of the car place or book where you look up the value of older cars ?

We have a Avanti Studebaker that we are going to sell and I want to get some kind of an idea as to what I might be able to get out of it but I can't remember the name of where I am supposed to look.I know it is not Kelly Bluebook but something else.Can someone please tell me ? Thanks.|||www.edmunds.com :)|||try kellybluebook.com