There are actually six Mary Poppins books

The heading really says it all for this one. I've not read the books but enjoyed the movie as a little girl and the stage show more recently. I might have to read the books now too.

The six books are called:

1. Mary Poppins
2. Mary Poppins Comes Back
3. Mary Poppins Opens the Door (gee whiz, that sounds like a page turner!)
4. Mary Poppins in the Park
5. Mary Poppins in Cherry Tree Lane
6. Mary Poppins and the House Next Door