Rockefeller Jr 's youngest son David would visit with his father .
Rockefeller Sr , urged by Rockefeller Jr , his only son , who was enthusiastic about the Institute , visited the University once .
son   's youngest son David would visit with Rockefeller Sr 's father .
Rockefeller Sr , urged by Rockefeller Jr , his only son , who was enthusiastic about the Institute , visited the University once .