On integral graphs which belong to the class <f><ovl type="bar" STYLE="S">αKa∪βKb,b</ovl></f>

Let <f>G</f> be a simple graph and let <f>&Gmacr;</f> denote its complement. We say that <f>G</f> is integral, if its spectrum consists of integral values. In this work we establish a characterization of integral graphs which belong to the class <f><ovl type="bar" STYLE="S">αKa∪βKb,b</ovl></f>, where <f>mG</f> denotes the <f>m</f>-fold union of the graph <f>G</f>. [Copyright &y& Elsevier]