I am studying a book on "Hyperbolic Geometry". It start with the The Lorentzian inner product $\langle x,y\rangle = x_1y_1+x_2y_2+\dots -x_ny_n$ on $\mathbb{R}^n.$
I find it interesting and want to learn about the Geometry of the space $\mathbb{R}^n$ equipped with an indefinite inner product.I know a book on indefinite inner product by J Bognar.
Please suggest me some books to learn the Geometry of the indefinite inner product space.