I’m sad, frustrated

Why I have to pay for Openstack operations guid book when it is availble free on http://docs.huihoo.com/openstack/docs.openstack.org/ops/ore

On June 18th I bought Openstack operations guide ebook (PDF) written by Tom Fiefield & co-autohrs. I have paid $31.99 for the book. Now I discover that same books is available free on: http://docs.huihoo.com/openstack/docs...
Now, I am not sure why I have to buy the book when it is freely available on net ? Please let me know if I can revert back my money I have paid
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