Do you mean this book:
http://www.diedunklenjahre.de/
?
Unfortunately it's 'ausverkauft', but you may try to write the author, maybe there is one last copy waiting for you. Or a reprint may be under consideration. Who knows...
If you are ready to pay a lot for this book, just buy it second hand from Amazon.de:
http://www.amazon.de/Die-dunklen-Jah.../dp/3000257489