Erratum to “The lollipop graph is determined by its Q-spectrum”

The proof of Theorem 3.3 in [Y. Zhang, X. Liu, B. Zhang, X. Yong, The lollipop graph is determined by its Q-spectrum, Discrete Math. 309 (2009) 3364–3369] is not correct. Actually, in the development of P A ( G 1 ) ( λ ) , the authors missed several products into addition, which makes the rest of the proof invalid. Note that the statement of the theorem is true. Here, we give a correct proof.