Day 30: My favorite English-language Romanov fiction novel is of course
The Lost Crown, and my favorite German historical novel is
Die Zarentochter by Petra Durst-Benning. It's about Tsar Nicholas I's second daughter, Grand Duchess Olga Nikolaevna, who later became queen of Wuerttemberg.
P.S. For anyone interested, there is a 30 day royalty-in-general challenge floating around the Internet right now