James Stevenson published a book in 2001 about the A-12 Avenger II, titled The $5 Billion Misunderstanding: The Collapse of the Navy’s A-12 Stealth Bomber Program, which discusses how developmental problems precipitated the A-12’s cancellation before any A-12 service test vehicles could be built.

As a side note, on January 23, 2014, the companies* involved in development of the A-12 reached a settlement with the Supreme Court regarding legal issues with the manner in which the A-12 program was canceled whereby General Dynamics and Boeing agreed to pay $200 million each to the US Navy.

*The McDonnell Douglas company which partnered with General Dynamics to develop the A-12 was acquired by Boeing in 1997, six years after the A-12 was canceled.

https://www.amazon.com/Billion-Misunderstanding-Collapse-12-Stealth/dp/…

https://www.reuters.com/article/boeing-generaldynamics-settlement-idUSL…