1. D. Atwood, S. K. Gupta, and A. Soni, Detecting fourth generation quarks at Hadron Colliders, J. High Energy Phys. 1206, 105 (2012), arXiv: 1104.3874 [hep-ph]
2. B. Holdom, W. S. Hou, T. Hurth, M. L. Mangano, S. Sultansoy, and G. Unel, Four statements about the fourth generation, PMC Phys. A3, 4 (2009), arXiv: 0904.4698 [hep-ph]
3. D. Fargion, Yu. A. Golubkov, M. Yu. Khlopov, R. V. Konoplich, and R. Mignani, Possible effects of the existence of the 4th Generation Neutrino, Pisma Zh. Eksp. Teor. Fiz. 69, 402 (1999); JETP Lett. 69, 434 (1999), arXiv: astro-ph/9903086
4. Y. Koide, fermion-boson composite model of quarks and leptons, Phys. Lett. B 120(1-3), 161 (1983)
5. Y. Koide, A new view of quark and lepton mass hierarchy, Phys. Rev. D 28, 252 (1983); Erratum: Phys. Rev. D 29, 1544 (1984)