You can see it here.
Basically, the authors obtained credit-score data for small businesses, and looked to see what changed when the federal minimum wage increased. Specifically, they compared states where the minimum wage actually rose with a control group — states that were not affected because they already required a higher minimum wage than the federal government did.
The result? Businesses dealing with minimum-wage hikes saw their credit scores decline, along with “lower bank credit, higher loan defaults, lower employment, [and] a lower entry and a higher exit rate.”