@article{LeLeMc2009b,
	Author = {T. Lee and M. Leok and {N. H.} McClamroch},
	Journal = {International Journal for Numerical Methods in Engineering},
	Number = {9},
	Pages = {1147--1174},
	Title = {Lagrangian Mechanics and Variational Integrators on Two-Spheres},
	Volume = {79},
	Year = {2009},
	doi={10.1002/nme.2603}
}