1001 Wristwatches from 1925 to Present Martin Haussermann Large-format hardcover book detailing a curated selection of wristwatches manufactured from 1925 through to the early 21st century. Includes models from manufacturers such as Blancpain, Hublot, Heuer, Junghans, Breuget, Baume and Mercier, and many more, with striking color photographs of each model presented and useful pairing captions for context. 295 pages
1-405494638
Parragon Inc
2006
Parragon Inc
Reference 
How can I know what year my Junghans German mantel clock is? It was a marriage gift for my grandmother who was married in 1910. It worked great and chimes (Westminster) on the 15 minutes and of course the mainspring winds as well. The hourly chime spring however snapped one time when I wound it decades ago tearing open my knuckles with the key <grimace> here it is… http://www.l-y-n-c-h.com/2019/content/20190623_112205_large.html Can you provide a spring for the hourly hammers chime?
Yes we have every mainspring size that is made in the modern world in our inventory.
Best to send the movement in for inspection, cleaning, and a quote. This is because often the break of the mainspring will cause a shock to the rest of the movement, and cause damage to the next wheel up from the spring.
See details on this service at this link
https://www.clockworks.com/clock-repair-service.html
If the clock in a barrel and you do not want to ship the entire movement, see this link
https://www.clockworks.com/product/hole-end-mainspring-replacement-service
To do it your self, see mainsprings to purchase here
https://www.clockworks.com/product/loop-end-clock-mainspring
and here
https://www.clockworks.com/product/hole-end-clock-mainspring
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com