Okay, I dug through the links in the article. I didn't immediately see links to any of the studies (one link to a union site's page about bullying, one HR-oriented guide to developing related policies, a link to what appears to be a formal book review, one link that seemed to be an actual study I can't find in a library, and other articles that discuss the issue).
One of the linked articles actually comments on my primary point, though with a different purpose:
If I missed a link to an actual study, help me out. I thought I clicked on every link in the article, but maybe I missed some. I checked some of the other sources I came across when searching for the linked study article - all with the same first author - but none provided an obvious reference to prevalence