1. M. Kostenko and L. Piotrovsky “ Electrical Machines ” Vol. 2 , Mir Publsihsers , Moscow , 1968 , PP. 50 .
2. B. Heller and V. Hamata “ Harmonic Field Effects in Induction Machines ” Academia, Publishing House of the Czechoslovak Academy of Sciences , Prague 1977 , PP. 26 .
3. K. Oberretl “ Field-Harmonic Theory of the squirrel cage Motor, Taking Multiple Armature Reaction and Parallel Winding Branches into account ” Translated into English, Arch fur Elektrotechnik, 49, 1065 , PP. 343 – 364 .
4. M. Krondl “ The paristic torques in Induction Machines ” Bulletin Oerlikon , 1931 , No. 124 , PP. 654 .