iBooks library location incorrect The volume containing my user folder was unexpectedly ejected, now iBooks wants the library to be in "Volume 1" instead of "Volume". Where is the preference file that tells it the location of the library?

Edit: I deleted ~/Library/Cookies/com.apple.ibooks.cookies, ~/Library/Containers/com.apple.iBooksX, and moved ~/Library/Containers/com.apple.BKAgentService to the desktop then logged out. iBooks now shows the library location as (null) and won't reset.
I restored the files that were moved and deleted then logged out and restarted, that resolved the issue.