Hot Puzzle

My nine year old son and I work on balloons Scramble Squares. For those of you who do not know what it is, the goal is to get the nine square pieces illustrated in a 12 "x 12" square so that the chart on the edges of the pieces "correspond perfectly to form a finished design in every direction. My son worked on the puzzle by hot air balloon for hours, but was not able to solve the puzzle. I hate for him to be so discouraged that it will not try another. Is there a site or book that shows the answers to this puzzle one? It may help to understand how it is done so that it can complete the puzzle that there are others.

Thank you for your help!

There are some sites that try to learn to solve scramble squares. I do not know if they will be helpful. They are complex. Take a look anyway because it does not seem to be other options.

Explanation
http://www.cs.rockhurst.edu/ ~ burger / Theresa ...
Trial:
http://www.cs.rockhurst.edu/ ~ burger / Theresa ...
Explanation and Info Imput data:
http://www.vandine.biz/scramble_solve.ph ...

Scramble Squares online:
http://www.b-dazzle.com/ScramblePuzzle.a ...

This puzzle was designed to take hours to resolve, then it is unlikely that there is a simple solution available. Good luck!