1. T Padmanabhan, Curr. Sci. 70, 784 (1996)
2. S Chandrasekhar, The Astrophys. J. 97, 255 (1943)
3. S Chandrasekhar, Rev. Mod. Phys. 21, 383 (1949)
4. The integral for $\mathcal{H}$ can be expressed exactly in terms of simple functions, although the expression is quite long. This is much easier to demonstrate nowadays than it was in the 1940s, with tools like Mathematica and Maple.
5. S Chandrasekhar and J von Neumann, The Astrophys. J. 95, 489 (1942)