531 for Football?

I have looked everywhere I can think of to buy this book and can’t seem to find it. Does anyone have any ideas? I found a thread on here about it but the link that was in the thread is bad. I have read both 531 books and am a huge fan. I would like to implement this system with my players but I am just not sure where the clean fits in with it. Thanks for the help folks.

It is no longer available for sale.

I own it, and use the hell out of it, Just curious, why is it not available anymore