A lot of horological reference books, titles including "Brittens Old Clocks and Watches and Their Makers" by Britten, "The Musical Clock" and "Restoring Musical Boxes and Musical Clocks" by Ord - Hume", "The Pendulum Clock" by Huygens, "European Pendulum Clocks" by Maurice, "Keeping Time" by Good, "Conservation of Clocks and Watches" by The British Horological Institute, "Beautiful Vienna Regulators of the 19th Century" by Kochaver,. "Vienna Regulators and Factory Clocks" by Ortenburger, "Spring Driven Dutch Pendulum Clocks" by Plomp, and others