[1] BUSSEMAKER F. C.-CVETKOVIC D.: There are exactly 13 connected cubic integral graphs. Publ. Elektrotech. Fak. Ser. Mat. Fiz. 544 (1976), 43-48. MR 0465944

[2] CVETKOVIC D.-DOOB M.-SACHS H.: Spectra of Graphs. VEB Deutscher Verlag d. Wiss, Berlin, 1980. MR 0572262 | Zbl 0458.05042

[3] HARARY F.: Graph Theory. Addison-Wesley, Reading Mass., 1969. MR 0256911 | Zbl 0196.27202

[4] HARARY F.-SCHWENK A. J.: Which graphs have integral spectra?. In: Graphs and Combinatorics. Lecture Notes in Math. 406, Springer-Verlag, Berlin, 1974, pp. 45-51. MR 0387124

[5] HARARY F.: Four difficult unsolved problems in graph theory. In: Recent Advances in Graph Theory, Academia, Praha, 1975, pp. 253-255. MR 0382042 | Zbl 0329.05125

[6] HIC P.-NEDELA R.-PAVLIKOVA S.: Front divisor of trees. Acta Math. Univ. Comenian. LXI (1992), 69-84. MR 1205861

[7] HIC P.-NEDELA R.: Note on zeros of the characteristic polynomial of balanced integral trees. Acta Univ. Mathaei Belii Ser. Math. 3 (1995), 31-35. MR 1409887

[8] LI X. L.-LIN G. N.: On integral trees problems. Kexue Tongbao (Chinese) 33 (1988), 802-806. MR 0963194

[9] LIU R. Y.: Integral trees of diameter 5. J. Systems Sci. Math. Sci. 8 (1988), 357-360. MR 0979677 | Zbl 0695.05016

[10] SCHWENK J. A.: Computing the characteristic polynomial of a graphs. In: Graphs and Combinatorics. Lecture notes in Math. 406, Springer-Verlag, Berlin, 1974, pp. 247-251. MR 0387126

[11] SCHWENK A. J.: Exactly thirteen connected cubic graphs have integral spectra. In: Notes in Math. Ser. A 642, Springer-Verlag, Berlin, 1978, pp. 516-533. MR 0499520 | Zbl 0376.05050

[12] SCHWENK A. J.-WATANABE M.: Integral starlike trees. J. Austral. Math. Soc. Ser. A 28 (1979), 120-128. MR 0541173 | Zbl 0428.05021

[13] WATANABE M.: Note on integral trees. Math. Rep. Toyama Univ. 2 (1979), 95-100. MR 0542382 | Zbl 0432.05019