By the time the sun began to bleed through the blinds, Leo felt a shift. The disjointed equations in his head were snapping into a cohesive structure. The PDF was more than a cheat sheet; it was a guided tour of the mind of a relativist.
: Problems involving curvature, Einstein field equations, Schwarzschild solution, and gravitational lensing. By the time the sun began to bleed
The PDF version of the book is widely available online. However, I encourage you to verify the authenticity and legitimacy of the source, as copyright laws may apply. Einstein field equations