Where can I read more about formula (G-T)= -(S-I) -(X-M)? And how is this formula called? I saw this formula in following context:

I want to create Banker State. It's supposed to rely on profit from loans instead of taxes. I would like to keep taxes as low as possible.
Reply: what you're trying to do wouldn't work unless you
were running massive trade surpluses (a la Saudi Arabia). The
government debt represents nongovernment sector equity. (G-T)= -(S-I)
-(X-M) The government fiscal deficit represents the nongovernment sector's net financial savings. Government trying to build positive
debt means forcing the nongovernment sector to go into debt simply
just to pay its tax bill. It doesn't work, it would create vertical
unemployment &amp; the automatic fiscal stabilizers would push the
government fiscal's position (which is reaction to nongovernment
sector spending behavior) into deficit.
Since you already answered yourself I am just filling the textbook recommendation:

You could  find more on this in Blanchard et al. Macroeconomics: an European Perspective. You will find this there (assuming based on the question you are looking something at undergraduate level).