- May 2014
Apparently it's this book:Is there a good source which gives Wilhelm's desire to actually annex Austria?
There's a big gap between inflicting a humiliating end to a campaign and advocating annexation. However, there's nothing enjoy more than being surprised by something I learn here.
Otto von Bismarck - Wikipedia
Steinberg, Jonathan (2011). Bismarck: A Life. Oxford University Press. ISBN 978-0199975396. -- page 253.