add links

[ShawnL00]

I figured out most of the cases. Here are the ones for which I could not find appropriate references:

#+LATEX: \contentid{linsolve_simple}
#+LATEX: \contentid{schur_complement}
#+LATEX: \contentid{lu_special}
#+LATEX: \contentid{solve_taylor}
#+LATEX: \contentid{numdiff_matrix}

[inducer]

Awesome, thanks! This is good validation, since it matches areas where I've deviated a bit from the book.

[inducer]

Thanks!