grammar - How do you casually describe in English a possession of thing(s) belonging to/shared by two people?

Neither of the following sounds quite "right" to me:

• This is the book of Kelly and I. (Maybe valid but still sounds too rigid)


• This book is of Kelly and mine's. (I know, sounds the weirdest)


• This is mine and Kelly's book.


• This book, Kelly and I own it.

In my native language (Indonesian) we have a phrase or a way of saying this without sounding weird or overly formal. Do you use any of the above at all, or is there any different sentence pattern for describing this kind of situation?