Studies on Feet Position on Squat

I’m very curious about what the scientific literature says about the angle of your feet during a back squat. I was of the opinion that you position your feet such that your knees track in line with them. However, I’m unable to find any studies that have been done on this.

The only thing I found that was even related was this:
Escamilla, R.F., et al. “Effects of technique variations on knee biomechanics during the squat and leg press.” Medicine & Science in Sports & Exercise 33.9 (Sep. 2001): 1552-1566.

And all it says is “… and two foot angle positions (feet straight and feet turned out 30 degrees). No differences were found in muscle activity or knee forces between foot angle variations.”

Does anyone know of any studies done that address this?