There was a full soundtrack recording of the wizard of oz how can I find it again?

It was a cette, a full recording of the movie with Judy Garland. Lines and songs as if you put the movie on and turned the screen off. I want to find it again but I have no idea if it had a special title or anything. My little sister used to listen to it at bed time and I'd love to find it and gift it for her birthday. Can anyone help me?