I tried to searching for an article but couldn't find it. The title is A Zero Wage Increase Again. MacMillian (2011)
Unfortunately Harvard Business Review's case studies are separeate from their journals and are not something we have access to. HBR's copyright restrictions are very specific and usually do not allow for copies to be made. I suggest contacting your professor who might be making the study availaible or is willing to put a copy on reserve with the library.