"Two small men with quick green eyes and bald heads studded with metal spikes and tattooed with shifting digital codes suggest for me a trip to someplace called Osgiliath." - Chapter 10, referencing a city from The Lord of the Rings.
House Barca - The name "Barca" is from the Carthaginian General Hannibal Barca.
"'So this kid is a what? A predestined Alexander? A Caesar? A Genghis? A Wiggin?'" - Darrow, Chapter 34, referencing the popular sci-fi book, "Ender's Game," which follows a space battle school trainee, Ender Wiggin.