1. Long, G.L., Wang, C., Li, Y.S., Deng, F.G.: Quantum secure direct communication. Sci. China (Physics, Mechanics and Astronomy) 41(4), 332–342 (2011)
2. Long, G.L., Qin, G.Q.: Quantum key distribution and quantum secure direct communication. Phys. Eng. 24(2), 3–12 (2014)
3. Lee, H., Yang, H.J., Lim, J.: Quantum direct communication with authentication. Phys. Rev. A 73(4), 543–543 (2005)
4. Yu-Guang, Y., Qiao-Yan, W., Fu-Chen, Z.: An efficient quantum secure direct communication scheme with authentication. Chin. Phys. B 16(7), 1838 (2007)
5. Sun, Z.W., Du, R.G., Long, D.Y.: Quantum secure direct communication with two-photon four-qubit cluster states. Int. J. Theor. Phys. 51(6), 1946–1952 (2012)