classification of groups whose vanishing elements are contained in exactly two conjugacy classes

Let g be a finite group . we say that an element g in g is a vanishing element if there exists some irreducible character χ of g such that χ(g) = 0 . moreover, the conjugacy class of a vanishing element is called a vanishing conjugacy class. in this paper , we classify groups with exactly two vanishing conjugacy classes and show that such groups are either frobenius or quasi-frobenius groups.