Daniel P. Sheehan has a great college lecture series available. He discusses all the connections between George Herbert Walker and Prescott Bush.

Rulers of the Realm Introduction: Daniel Sheehan:

https://www.youtube.com/watch?v=xAcT8Nt_j0Q&list=PLxk5V3uxvfq8d_nL_QdMEvSSpnMB-x3_A

Flowchart:

https://static1.squarespace.com/static/515d04a3e4b054dae3fecc34/t/57ed2c949de4bb2283f7f2fa/1475161255287/RotR+flow+chart-02.png