"The Watch & Clock Makers' Handbook, Dictionary and Guide", Frederick James Britten, 11 upplagan, 1976. Horological Hints and Helps, 1950. Watch and Clock Making David Glasgow, 1977. It's about time, Paul M Chamberlain, 1978. Watch and Clock Making and Repairing, W. J. Gazeley, 1975. Die Hemmungen der Uhren, Conrad Dietzschold, 1980.Practical Watch Adjusting, Donald de Carle, 1973. Practical Clock Repairing, Donald de Carle, 1968. The Craft of the Clockmaker, E. J. Tyler, 1973. URMAKARE I ESKILSTUNA, Jörgen Lindkvist, 1979. The Science of Clocks and Watches , A L Rawlings, 1974. Practical Watch Repairing, Donald De Carle, 1957.
Wear due to age and use. Unexamined.