1. J C Pati and A Salam, Phys. Rev. D 10, 275 (1974), Erratum, ibid. D 11, 703 (1975)
2. C S Aulakh, Fermion mass hierarchy in the Nu MSGUT. I. The Real core, hep-ph/0602132
3. P Minkowski, Phys. Lett. B 67, 110 (1977) M Gell-Mann, P Ramond and R Slansky, in: Supergravity edited by P van Niewenhuizen and D Z Freedman (North Holland, 1979) T Yanagida, in: Proceedings of Workshop on Unified Theory and Baryon number in the Universe edited by O Sawada and A Sugamoto (KEK, 1979) R N Mohapatra and G Senjanović, Phys. Rev. Lett. 44, 912 (1980) R N Mohapatra and G Senjanović, Phys. Rev. D 23, 165 (1981) G Lazarides, Q Shafi and C Wetterich, Nucl. Phys. B 181, 287 (1981)
4. C S Aulakh, A Melfo and G Senjanovic, Phys. Rev. D 57, 4174 (1998), hep-ph/9707256 C S Aulakh, K Benakli and G Senjanovic, Phys. Rev. Lett. 79, 2188 (1997), hep-ph/9703434
5. C S Aulakh, B Bajc, A Melfo, A Rasin and G Senjanovic, Nucl. Phys. B 597, 89 (2001), hep-ph/0004031