Shweta, R.K.Padmashini,. “LEVEL SHIFT AND PHASE SHIFT MODULATION FOR NINE LEVEL INVERTERS”. International Journal of Advanced Science and Technology 29, no. 4s (March 19, 2020): 1022 - 1033. Accessed October 6, 2022. https://sersc.org/journals/index.php/IJAST/article/view/6605.