What controlled test have been done to verify loose strings are for power and tight strings are for control?

Re: tennis racket string tension: Can someone direct me to the test results and verification report showing that tennis racket string tension determines that looser strings equal greater power and tighter strings equal more control? I know this has been believed since the 70's, but I have never seen documentation of a controlled test to confirm this finding. For my play, I find that tighter string tension results in both power and control. It seemed to work for Borg also. He strung his racket around 75 and had super power, great topspin, and superb control.