Help with odd number dividers (digital)

Question

I am reading this: http://www.onsemi.com/pub_link/Collateral/AND8001-D.PDF

On page three, the logic equations is given for the divide-by 9 DFF circuit. How do I obtain the equations through k-maps? I know to use k-maps, but I dont know what and how they are filling the k-maps with to obtain:

Ad = A*B* Bd = A*B + AB* 
Cd = ABC* + CB* + A*C Dd = ABC

Any illustrations appreciated.