Hi,
Iagree with the above post.To understand the movements occuring in the joint complex there is a need for imagination while going through the books mentioned.
I will suggest you to use a method which helped me.Take a square card and hold the card with your index fingers on the middle of lateral borders.Imagine that the upper border is the sacral base,Index fingers are on the inferior lateral angles.Then try to follow the movement of sacrum in card while reading various movements.