Angular momentum bounds in particle systems
  Four expressions involving sums of position and velocity coordinates bounding
the total angular momentum of particle systems, and by extension of any
continuous or discontinuous material systems, are derived which are tighter for
any particle configuration than similar inequalities derived by Sundman (1913),
Saari (2005) and Scheeres (2012). Eight distinct inequalities can thus be
ordered according to their tightness to angular momentum.
