A good help to address death

I was looking for a book to answer very specific questions of my 4 year old son's death. J needed to be accompanied to not make it a taboo subject or anxiety.
This book had clicked on it once the book ends the subject was closed. The words are simple and accurate, a bit outdated but it did the illustrations embarrassed.
It takes a lot to this little book and looks from time to time but it seems merciful compared to this.