I just finished Unsigned by Julie Kaewert, one of her series of Booklover mysteries.

I wrote about one of the other books in this series here and I don't know if I have anything new to add. They are enjoyable books, even if the overall shape of the plot is very similar from book to book - protagonist discovers some kind of historical secret related to books/publishing, gets chased around while his friends keep secrets from him to protect him. Eventually he muddles through and finds out all the truth.