A Matter of Time
Book containing TONS of detailed insider Gruen information
MANY new details on Gruen's history
The book "A Matter of Time - The Story of the Watch" by James Remington McCarthy has an enormous part of the book devoted to the Gruen watch company. Almost all aspects of the company have some amount of information added that wasn't previously known, including details on how Gruen designed their watches, manufactured them, the company's marketing focus on fashion, etc.
* Rights for using the text and images - Google has deemed this content to be "Public Domain". This give wide usage abilities for things like distribution, etc. So, go to town on the stuff!