David Griffiths' E&M text has a number of very large problems, among which is a veritable multitude of r's. There's
For some reason, Griffiths wanted to mask the complexity of his formulas, opting instead to confuse the reader with too many symbols which often have ambiguous meanings. Of course, this (and the many, many other problems) doesn't stop it from being the go-to E&M textbook for junior and senior level physics majors across the country. Hey, at least it's better than HRK.