This mantra is available in Panchapanchika puja of Sri Chakra Navavarana. You may refer Sri Raviji's book titled "Understanding and Worshipping Sri Chakra" Pancha panchika section. This is the third mantra in Pancha Ratnamba.
I have been doing Japa of Mother for quite some time now. I have been noticing for the last couple of days that when I am doing the Japa, I feel some kind of throbbing or heaviness between my eye brows just above the nose. It lasts for sometime after I stop the Japa.
Can you please tell me if it's good/bad or what is the significance of it.