What primary sources show studio control and the 1950s agency shift?

[Zachary_T]

I'm a film history graduate student focusing on studio system economics, and I'm researching how the rigid star contracts and vertical integration of the Golden Age of Hollywood not only created iconic films but also systematically controlled the public and private lives of actors. My current project examines the transition of power from studio heads to talent agencies in the late 1950s. For other scholars or enthusiasts of the era, what are some of the most revealing primary sources or lesser-known case studies that illustrate the extreme level of control studios exerted, and how did this factory-like production model ultimately contribute to both the artistic consistency and the creative stagnation that led to the system's collapse? I'm looking beyond the well-told stories of figures like Mayer and Warner.