About O'Raifeartaigh's theorem
Annales de l'institut Henri Poincaré. Section A, Physique Théorique, Tome 9 (1968) no. 1, pp. 7-16. 
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     author = {Fuchs, G\'erard},
     title = {About {O'Raifeartaigh's} theorem},
     journal = {Annales de l'institut Henri Poincar\'e. Section A, Physique Th\'eorique},
     pages = {7--16},
     publisher = {Gauthier-Villars},
     volume = {9},
     number = {1},
     year = {1968},
     mrnumber = {241063},
     zbl = {0162.58201},
     language = {en},
     url = {http://www.numdam.org/item/AIHPA_1968__9_1_7_0/}
}
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Fuchs, Gérard. About O'Raifeartaigh's theorem. Annales de l'institut Henri Poincaré. Section A, Physique Théorique, Tome 9 (1968) no. 1, pp. 7-16. http://www.numdam.org/item/AIHPA_1968__9_1_7_0/

[1] A.O. Barut and R. Raczka, On classification of non compact real simple Lie groups, Trieste, 1965. | MR | Zbl

[2] C. George and M. Leyy-Nahas, Finite dimensional representations of some non semisimple Lie algebras. J. M. P., Vol. 7, 6, 1966. | MR | Zbl