WANG, JianFeng, HUANG, Qiongxiang, BELARDO, Francesco and LI MARZI, Enzo M., 2009, A note on the spectral characterization of dumbbell graphs. [online]. 2009. Vol. 431, no. 10, p. 1707–1714. [Accessed 2 April 2025]. DOI 10.1016/j.laa.2009.06.009. Retrieved from: http://ac.els-cdn.com/S0024379509003000/1-s2.0-S0024379509003000-main.pdf?_tid=8b1812e6-a6d1-11e4-9be3-00000aacb35e&acdnat=1422438144_df490d3c40e5ab653ce6bb2ac13236fe